The fluorescent lights are flickering, the mirror is clearly (clearly!) warped, you're dripping with sweat. Standing there crammed into a pair of jeans two sizes too small, you become grimly resigned to the fact that you look more like an overweight haddock than the shapely denim god of your imagination.
Most teenagers will find any reason under the sun not to do their homework. But 16-year-old South Londoner Nick D'Aloisio's excuse is better than most - he has been busy developing an app which has made international headlines and attracted a big investment from a Hong Kong-based billionaire.