graffiti
One morning assembly the large, stern man that was our headmaster addressed the whole school, telling us the disgusting graffiti had to stop. The filthy language, unkind words, salacious rumours; it was not becoming of young gentlemen. They were simply NOT going to stand for it any more.
Later that very day I snuck up to the deputy head's office door, drew my symbol of defiance and wrote,

'GRAFFITI: nuff said fatty.'

Despite a massively over-dramatic 'inquisition' where they told us 'the perpetrator of this act WILL be punished', thinking back it was a pretty lame, inconsequential challenge on authority but at the time I felt invincible because I was never caught. Even though they tracked it down to someone who did art within the week, I guess I just have an honest face for a lying bastard.
Still, it was probably the finest cock and balls I have ever drawn.
(quibble, Sun 11 Sep 2011, 22:29, Reply)