1) Is someone is sitting out, they are your chips. It goes both ways. If you have a problem and are sitting out, they get to steal from you. No biggie.
2) When a shorty is all-in, the silent agreement to limp/check to eliminate him is only in effect when eliminating the person is more meaningful than getting chips. If there's 100 players left in a 180 player S&G, and someone puts his last $200 in, I raise with a good hand because I'm miles from the bubble and building a big pot with my big hand is more important than some insignificant knockout.
However, if we're on the bubble in a Double-or-Northing game and a shorty shoves, gets two callers, and I wake up with vowels, I'm checking it down. Chances are those first two callers were only doing it to team up to knock the dude out, and we have a better chance of doing that by teaming up. And at that point, me getting chips doesn't matter.
3) You are not allowed to tell people what you had in a tournament. Lie or don't tell.
Sometimes I'll say something like, "I probably had you beat," whether I did or not.
Or if there's anything else that people normally do in online games (or even live games) that make you angry simply because it's rude, say so.
I hate it when people tap the fish tank in ring games.
Making fun or taunting a bad player only causes them to tighten up or leave. Why scare off the easy money?