Kids usually write other poeples names on the unattended blackboard - ie smudger is a twat, or some such similar. Being a bit dim I thought no one would be stupid enough to write their own name on a board, so I did, thinking that someone else, anyone else, would get the blame. Unfortunately, there being no markers around, I used one from Terry's pencil case, and it was a permanent marker. so the words 'Jon Robinson wrote this!' remained on the board for a whole week, as no one would own up to writing it. They eventually came off with lots of rubbing.