There are SO many pranks you can pull on your friends, they all depend on how much you want to risk (which would seem to be very little seeing as how you don’t want to get in trouble), how much time/ effort you are willing to spend, and how much money you are willing to invest. If you can find a phone they don’t know the number to, prank calls are a GREAT idea. Popping out and scaring them is usually really fun and costs very little, if anything. Also try Scary Maze at http://www.maniacworld.com/maze_game.htm for a HUGE laugh. Whoopie cushions, joy buzzers, shock gum/ pens, exploding golf balls, and other props are also classic. http://www.prank.org/ has a lot of these. In general, the best pranks are those that no one has seen before, so be creative! Hope this helped!