Umm, let me see there was a thread simaliar to this a while back entitled something like " What do you do when your bored in class?" or something like that.
Make ruler/pen guns. This is where you grab a ruler preferable a wooden one and make a hole in the middle, then you grab a few rubber band rap 'em round and wahla, you have a launcher all you need now is a pen - put it through the hole and have the rubber bands on the back of it, you have now finshed it feel free to shoot at everybody or every one with it, good fun.
Random talking usually gets people.
A little off topic but once my older sister saw how much home work she had then she through it out of a second story window and some how locked a teacher in the cupboard.