Taking inspiration from my kids here...
Drink your drink with a straw, blow bubbles with it, and slurp loudly.
Make a mess and don't tidy it up. Or if you're too much of a neat freak, do the opposite - tidy up everyone else's things and put them in annoying places so they can't find stuff 
Stick two fingers up at someone annoying and poke your tongue out at them behind their back.
Stamp your feet and whine if your partner asks you to do something you don't fancy. Or just fold your arms, stick your bottom lip out and huff.
Have your music up too loud. Ignore requests to turn it down. Drive around with loud music on too, and your windows down.
Steal chips etc from your friend's or family's plates.
Burp and fart loudly and don't say pardon.
Hog everything and don't share - the TV remote, chocolate, the duvet, etc. Say 'me first!' and insist on doing everything first - first to sit down and eat dinner, pudding, etc.
Ruin/destroy something you don't like anymore. Rip up an ugly old t-shirt, stomp on it, put it in the bin etc. (Obviously pick something that isn't too wasteful)
Interrupt people and go 'la la la, boringgggg' if they talk about something you are not interested in.
Call everyone childish names - fartybum, stinkface, poohead etc.