Sleepover Prank Wars!

Okay, my friend is planning a birthday sleepover. Our whole group of friends will be there. My friend (the hostess), my other friend, and I have formed a secret alliance for a prank war. We will be pranking everyone else, and we need good pranks to play on them. I`ve already found a couple, but more would be nice... Anyways, we`re teenage girls, that`s what we do. So, if you have any good pranks, let me know! Thanks!