to go into one of your mates' bedrooms, and hide somewhere, and wait until they've fallen asleep, and then put a really creepy mask on (and lots and lots of layers of clothing, to completely disguise your shape beyond recognition, and make you look a little like a homeless person) and get some little LEDs to put in the eyes to make them glow red, and then when they're asleep, crouch at the bottom of their bed, and slowly reach under the covers and grab their foot, give it a pull, then when they wake up shocked, shout and gibber like a maniac and then run out of the room?

or would it make you some kind of criminal?