Having cornered the marble market in his first year, in his second year Marcus Mellor rapidly established himself as the pornography kingpin of our school.
He dealt his grubby wares from a large, tatty, black briefcase held together with masking tape, and always filled to bursting point with an seemingly unlimited quantity of top-shelf magazines.
His empire came to an abrupt and spectacular end. Running to a lesson, his briefcase burst open, spilling Clubs, Razzles, Fiestas and Mayfairs in a slithering tide down the stairs. Despite his desperate entreaties, they were hoovered up within seconds by a huge crowd of unbelieving boys. I still can't watch aid convoys arrive in famine-stricken towns without being reminded of the event.

I can claim superiority: I ran a similar operation in the last year of primary school. So not only was I really young, but I am also a girl, and was even then.
I would steal the raw material from under my best friend's brother's bed, cut out the best bits, and staple them together into little booklets, with plain covers onto which the boys could write "The Battle of Agincourt", or something. These little creations would sell for 50p.
(No thanks to the fusty careers adviser, I now get paid for doing something not entirely dissimilar.)

In boarding school, porn becomes currency as well as pasttime, like cigarettes in prison. Upon returning to my cell one eveing, I found the lockerful of porn had been forced open and emptied. A CSI style investigation led to the culprit, but much of the porn had already been broken down and sold on, making it impossible to recover. The record was thirty five pounds for a single jazz mag, making it an unusually expensive cheapie.