It is the first time the charity has specifically campaigned for volunteers from black and minority ethnic backgrounds.
'You got any better ideas?' encourages black men to help raise the aspirations of 5 to 11 year-olds in north London. Chance UK hopes the campaign will overturn a chronic shortage of black male volunteers.
"Some 85 per cent of our children are boys, and 61 per cent are from BME communities, but only 30 per cent of our mentors are men and only 40 per cent are black," said Gracia McGrath, Chance UK chief executive.
The campaign's images appear on bus tickets, billboards, postcards and ad vans in and around the Tottenham area, to capitalise on its very large young BME community. They target 18 to 35 year-olds.
McGrath said the images were deliberately stark because "we want men to understand how much is expected of them". She said men were attracted by the call for a practical response.
Posters will feature on 20 billboards and 100 bus stop shelters this month, and 10,000 postcards will be placed in north London pubs and clubs.
The charity has also targeted black men attending home matches at Tottenham Hotspur FC. Fans outside the ground when the club lost to Chelsea earlier this month were met by ad bikes and handed postcards. The ploy will be repeated during a fixture on 5 February.
Chance UK tasted early success after the "I wanna be a dealer" image began appearing on 100,000 bus tickets on Tottenham routes earlier this month. Twenty men applied to become mentors in four days.
"We would like this campaign to translate into at least 60 new mentors from BME community volunteers," said McGrath.
The campaign emerged after the charity won £36,000 worth of advertising space in a competition run by paper manufacturer Sappi. The charity was entered by long-time supporter and PR company Vitamin V.