Hide in a box and leave it a little bit OPEN then when someone comes jump out! (IT'LL BE SO FUNNY)
Play dress up with your little brother. Put a dress on him then take a photo...superglue it into the family album.
Tell your little sibling that you are secretly a vampire and you will suck their brains out tonight.
Go up to someone and shout at them with a Russian accent, "You have body of slim boy with even little to no butt."
Have a better idea for this list? Send it on in!