If anything I'm about to say below angers you, please remember this: I am not talking about you. I am talking about other people. When you do these things I find it charming and funny.
Also, the following are just my opinions, I can't force you to do anything (until I perfect my hypno-ray).
Before going to a public event, please turn off all cellphones, pagers, light sabers, squeaky shoes, monkeys etc
Gestures that have sounds that come from movies, tv shows, etc are funny exactly once and then never again.
If it's a watching sort of event come in and sit down as soon as possible.
If it's a participating sort of event, and your not participating, back off to observer areas.
If the person running the event is chatting something, STOP TALKING. If you're not interested in what the person running the event is saying, why are you here?
If you arrive late at an event, or happen on an event in progress, don't hover over the area and shout "HI EVERYONE I'M HERE, WHAT'S GOING ON?!", sit down and IM someone you know to find out what's going on.
Similarly if someone you know arrives at an event in progress, don't chat "hi so-and-so", IM them.
If your client starts acting weird and you're getting lag issues, please don't run around screaming "MY CLIENT IS ACTING WERID AND I'M GETTING LAG ISSUES", log out and log back in. If that doesn't work then the sim is too full and there's nothing anyone can do.
I invite your comments, but before you do, please read the first two paragraphs again.