To send a chat request to someone over an instant messanger like MSN or Yahoo the instant they log in with some random hello or strange quote.
Mech clicks login
0.5 seconds later
Neon: Hi, did you know kittens are furry?
Mech: HOLY HELL, stop being such a chat sniper fool. At least let the email warning come through first!!!!
When one enters a chat room and watches for idiots, then, when the opportunity arises, tosses in a biting comment at very random times to humiliate the idiot.
So, I'm watching this guy Driss in chat, and he completely lied 5 minutes ago by stating something totally contradictory, so, I became a Chat Sniper and made fun of him.