urm...i cant think of anything off the top of my head, maybe set fire to my self, cuz i was bord but i hav done loads of things, just cant think at the moment
setting fire to yourself is fun, but stupid, but also fun, but also stupi, but its so fun...*continues for 4 hours like this*
get a pair of walking sticks and give one to your friend and start sword fighting with them. Its not stupid but its fun.
I've done it with rulers at school before, starting playing star wars