At four o'clock in the afternoon last Friday, June 11, twenty-two young men lined up in a delirious stadium in Johannesburg, South Africa, and kicked off the biggest global event of all time: the 2010 FIFA World Cup. For four weeks, half the planet -- three billion people -- will be glued to their TVs and computers watching the games. And at half-time, they will be serenaded by a skinny Somali singer in baggy pants and a fedora, the voice of the biggest global marketing campaign ever undertaken by the world's most iconic brand, Coca-Cola.

The singer in the Coke ads is K'Naan, a former refugee from one of the poorest, most violent cities on earth. And all across the globe, people are humming the irresistible chorus to his official World Cup song, "Wavin' Flag":

"When I get older/I will be stronger/They'll call me freedom/Just like a wavin' flag."

The road to global stardom has had many twists and turns, a hip-hop fairytale even Hollywood would shy away from. K'Naan has lived through civil war, seen friends shot dead before his eyes, spent months in jail, been beaten up by bouncers in a Swedish nightclub. And now he's travelling the world in Coca-Cola's World Cup jet, singing about unity and celebration.

So why did a multinational soft drinks conglomerate choose a third-world rebel icon to front its campaign? A practising Muslim who lived the horror of war as a boy and who raps against injustice and oppression?

The answer lies in Africa, the world's last emerging market, where music and soccer have huge grassroots appeal -- and massive marketing potential. Coke wanted a developing-world star, a modern-day Bob Marley with street cred. They found him in K'Naan.

Grandson of a poet

In person, K'Naan is an unlikely star. He's very slim, with a shy, languid manner. He doesn't go for the bling-bling fashions of American rappers, instead favouring natty waistcoats over loose trousers, barely held up by impossibly slender hips. On top of his wild curly hair sits the inevitable fedora, cocked just so.

He is a thoughtful, quiet, intelligent man. He's 32, married with two young kids, but could pass for a teenager. He doesn't drink alcohol or smoke or do drugs, and tries to pray the requisite five times a day. Which makes him an unlikely spokesman for a multinational beverage behemoth with 13 brands worth more than a billion dollars each, including Coca-Cola, Diet Coke, Fanta, Minute Maid and Powerade.

K'Naan was born Keinan Warsame in Mogadishu, the Somali capital. He remembers his first years as happy. He grew up surrounded by poetry and song. His grandfather, Haji Mohamed, was a revered poet, and his late aunt, Magool, was one of the country's most famous singers. K'Naan remembers her singing him to sleep at night when he was a boy.

He regularly refers to his home country as the Nation of Poets.

"That's not a term of mine," he insists. "It's a very old term for Somalia, and a very powerful one, widely known... It's so important, how we feel the world is through our words. Generally the memory bank of Somalis is expansive, we feel like that's our biggest kind of universal contribution, is how our people express themselves, through poetry."

K'Naan's other source of joy was playing football. "It's something that we all love in Somalia, especially the children. Our national sport. Every kid plays it in every alleyway."

Truth to power

Neither football nor poetry could keep death out of Mogadishu. In the late 1980s, Somalia began to sink into civil war. Refugees from the north poured into the capital, followed by soldiers. K'Naan's neighbourhood got a new nickname: Rivers of Blood.

He fired his first gun at age eight. At 11, gunmen chased him and three friends through the streets. K'Naan escaped, but his friends were all killed.

Another day, he found an interesting-looking rock in the playground. He picked it up and threw it and blew up half a school building. It was a stray grenade.

In January 1991, just as rebel forces entered Mogadishu, K'Naan's mother managed to bundle her three kids onto the last commercial flight to leave the city. The airport is still closed, and the country has been at war ever since; conservative estimates say half a million people have died.

The family ended up in the Dixon Road area of Toronto. Also known as Little Mogadishu, its rundown high-rises are home to a quarter of Canada's 100,000 Somali immigrants. K'Naan didn't finish high school and had some run-ins with the law, but he never stopped writing poetry and songs, and soon had a reputation for eloquence among the Somali community.

Success came with an unlikely appearance at a concert in Geneva celebrating the 50th anniversary of the United Nations' 1951 Refugee Convention. K'Naan still isn't sure why they invited him, but he wasn't going to miss his chance. He performed a short song that had been vetted by the UN bureaucrats, but then kept going, launching into a startling off-the cuff rap denouncing the U.N.'s failures in Somalia.

The diplomats looked on, quietly appalled, but when he finished, they stood up and applauded. In the crowd was the great Senegalese singer Youssou N'Dour, who shouted "magnifique, magnifique" again and again. Impressed by the young man's torrent of words, not to mention his bravery, Africa's most popular musician asked K'Naan to join him in the studio, and then on a world tour.

Coke comes calling

Looking back on that watershed moment, K'Naan says, "I didn't do it for provocation, I didn't do it for sensation. It was a bit more personal for me. As someone who is from Somalia, and has a strong community at home, I have more affinity to my people than to my career, and to be present representing Somalia on such a stage, and to say nothing in that moment..." He searches for the right word. "It would have felt a little unjustified."

Four years later, in 2005, K'Naan released his first album, The Dusty Foot Philosopher. It was a rich and sprawling collection of songs combining wonderful melodies with African rhythms and American hip-hop and folk. Many of the songs were angry but others were tender and yearning, and the lyrics were rich and heartfelt. The album won him a Juno and a Best Newcomer in World Music award from the BBC.

"Wavin' Flag" was one of the standout tracks on K'Naan's second album, Troubadour, released in 2009. His star had been quietly rising: a big label deal, tours with the likes of Lenny Kravitz and Damian Marley, a plug on Kanye West's blog (for the song "America," which features some verses in Somali and a gorgeous Ethiopian-style horn riff). But the Coke deal has taken his reach to a whole new level.

"K'Naan has a unique sound," explains Petro Kacur, senior manager of marketing communications for the Coca-Cola Company. The company wanted an African musician to front its campaign, and they loved the uplifting feeling of "Wavin' Flag."

"The song has huge potential. It is rooted in Africa but has global appeal. And he shares our vision, of optimism, happiness and celebration."

That seems like a bit of a stretch, given that the original version of "Wavin' Flag" features bittersweet lyrics like "So many wars, settling scores/Bringing us promises, leaving us poor." But K'Naan seems to have sincerely embraced Coke's message of unity and peace. At the company's bidding, he wrote and recorded a new version, the "World Cup Celebration Mix," that opens with a mighty barrage of drums and asks us to "rejoice in the beautiful game/Then together celebrate the day."

World Cup publicity tour

Last November, K'Naan headed for Nairobi to join the African leg of the "World Cup Trophy Tour with Coca-Cola." This massive marketing venture visited every single African country -- except, irony would have it, Somalia, which was judged too dangerous -- then continued around the globe until May, covering 134,000 kilometres and 86 nations.

In every one, potential Coke drinkers were serenaded with "Wavin' Flag" and photographed with the World Cup trophy. K'Naan performed in 12 of the African countries and several others, including whistle stops in Japan, Mexico, Brazil, the U.K., France, Paris and Slovenia.

He recognizes Coke's courage in choosing him as their poster boy. "I actually give them credit for that one. A big company like that, that has a lot at stake, their reputation is not exactly for taking risks. To pick someone like me, who speaks their mind, and writes music that is a little more philosophical, yeah, that's brave."

He then points out that the music he is making now is full of hope. "A lot of my songs are still weighty, but they don't stay there, they don't stay in anger, they don't linger in sadness, they address it and kind of fall into the light... That's the sentiment that people care about."

He says people often listen to his music for the first time and get up and dance. "But if you listen to the song, the story alone, there's something else to focus on."

'Wavin' Flag' goes global

Coke and K'Naan have now released 20 different versions of "Wavin' Flag," each one a bilingual duet with a local musical star. The Spanish-language version, featuring crooner David Bisbal, was a number one hit in several countries. Other versions feature verses in Brazilian Portuguese, Mandarin, French, Greek, Japanese, Nigerian, Vietnamese, Indonesian, Thai, Haitian French and the South African language Setswana.

The Arabic take, "Wavin' Flag / Shagga' Bi Alamak Da," features breathy vocals from Lebanese pop diva Nancy Ajram. It is one of K'Naan's favourites, not least because he speaks the language a little himself. "It sounds so beautiful. It's almost like the words were meant to be sung in Arabic," he says with a laugh. "Yeah, the moment before the chorus when she says habibi ['darling'] -- it's so, yeah, it's incredibly sexy."

A major force behind K'Naan's success is his manager, Sol Guy. Asked why he chose to hitch K'Naan's wagon to the biggest brand on the planet, Guy laughs. "As long as it doesn't compromise the song, the message, I'm fine with it." And in this day and age, when no one in the music business is making money selling CDs, it's a clever way to get his artist heard.

"Do you think these huge corporations don't know what they're doing, when they put a skinny refugee guy who sings about redemption, Marley style, at the heart of their campaign?"

'A country disguised as a person'

Both Guy and K'Naan have struggled with these choices. Is a deal with Coke a pact with the devil, or is it just smart? Four years ago, they couldn't decide if they should play at the Canadian Live8 concert alongside a line-up of wrinkly rockers. But it was for Africa, so they did.

"And it was the highlight for a lot of people, here and all over the world," says Guy. "This skinny Somali kid singing with his friend on drums. 'Until the Lion Learns to Speak' [a track from The Dusty Foot Philosopher] -- that blew a lot of people away."

Social entrepreneurship, social venture, more-than-profit, whatever you want to call it, "It's doing the right thing. The blue chips these days, they are talking about the three Ps: profit, people, the planet. Cool culture shifts a lot. It matters now to give a shit. You're all invited to the party; it doesn't matter what you did before."

In a piece he published recently in The Huffington Post, K'Naan wrote that he hoped his "music opened an eye or two... to my own life, written as a country disguised as a person." Asked what he meant by that, he explains that "If you pay attention to how I write, what I write, it's almost as if I'm writing about a collective experience, rather that just my personal life... trying to make sense of our identity."

"These things are things I've carried with me, sometimes alone, sometimes on behalf of the millions of Somalis. I've written it, I hope, in a way that would make them proud, and make them, as well, kinda self-critical."

He tells a story of meeting a Somali academic in the U.S. who thanked him for conducting a mass therapy session for Somalis in his songs. "Which is a remarkable compliment and a statement, you know."

Rooting for Africa

The downside of being one of the country's best-known faces is being called by the BBC to comment on piracy or other political issues, like the recent move to ban music on the radio in Mogadishu. With success comes a responsibility to the community.

"Yeah, it's powerful," he admits. "And it wasn't like it was a self-appointed choice, it's not something I chose, it's just something that has to be done. I'm doing it, but I'd prefer just to be making songs... I try to carry it, shoulder it like a sack of bones, rather than a burden, you know."

Since last week's World Cup kick-off, the media coverage has been intense. And it is hard to avoid that irresistible chorus; it is being played before and during every game, and two ads featuring it will be running incessantly throughout the tournament in 160 nations; "every country on earth, basically," in Kacur's words.

Including Somalia. Though the country did not qualify for the World Cup; the security situation meant they weren't allowed to play any matches at home, and they got knocked out in the first qualifying round, by minnows Djibouti (population, 864,000).

So who will K'Naan be supporting?

"I'm going for Ivory Coast," he says. “I hope [striker Didier] Drogba recovers, gets back in the game."

"But just generally I'm supporting any African team, really. It would be such a beautiful thing if an African team took it home. Wouldn't it?"