Always prove them wrong, and convince them that they are, in fact, wrong. Even when they are not. Argue until you're cross-eyed.
Hum a lot.
Throw light objects at them (for instance crisps).
Eat all their food.
Kick them repeatedly in the shins.
Make them answer stupid polls (ahem!).
Send them junk mail/post.
Other (must specify)
Always prove them wrong, and convince them that they are, in fact, wrong. Even when they are not. Argue until you're cross-eyed.