Forget the punch line to a long joke, but assure the listener it was a "real hoot".
Follow a few paces behind someone, spraying everything they touch with a can of Lysol.

Practice making fax and modem noises.
Highlight irrelevant information in scientific papers and copy them to your boss.

Leave your turn signal on for fifty miles.

Make beeping noises when a large person backs up.

Invent nonsense computer jargon in conversations, and see if people play along to avoid looking ignorant.
Erect an elaborate network of ropes in your backyard, and tell the neighbors you are a "spider person".
Wear a special hip holster for your remote control.
Signal that a conversation is over by clamping your hands over your ears.

Give a play-by-play account of a person's every action in a nasal Howard Cossell voice.
To really annoy people, stand on a street corner, pointing a hair dryer at passing traffic, and watch it slow down.
Specify that your drive-through order is "to go".

Holler random numbers while someone is counting.
Take a sock puppet to dinner with you. When the waiter comes to ask you what you want, consult the sock. When the check comes argue with the sock loud enough so everyone can hear you about who will pay the bill, throw him down and say, "Fine you pay!" Then leave.