Empty out a bleach bottle and refill it with milk. Carry it around and drink from it . For best effect, bring a cup along too.
Put on socks, spray the floor with Pledge, and slide around (works best with hardwood floor).
Sit in your best friends lawn dressed as a doll/creepy thing, stay there until someone sees you, and grab their leg.
Text your best friend if the want to come over for a fish slapping party (see there responses) have a can of sardines (see the reaction)XD XD XD.
Randomly text your best friend and say you need to ask them something super important, but make a long paragraph. When they say what is it, ask if they know where the gingerbread man is
Listen to the song "Take A Hint" until you can memorize it then go preform it with your best friend in the middle of any public area (such as a mall, park, etc.).
Have a better idea for this list? Send it on in!