When I was at uni, living in halls, the lads on my corridor were in my room watching Shooting Stars on telly, and one of them threw an empty crisp packet on the floor, and said "I bet you can't wait to the end of the programme before picking that up". I tried to just stare at the screen, but I only lasted about a minute before having to put it in the bin. When I'd go out to the loo, they'd quickly move posters on my wall, so they weren't quite straight, and then laugh as I sorted it all out. I also can't walk on the cracks between paving stones. Quite odd, as I'm probably messy in other ways.