Meaning "Back, bitch(es)!" Typically used in chat rooms after returning from AFK.
An appropriate response to this message is "wbcx", which stands for "Welcome back, bitch!"
(In a chat room)
(...a number of minutes later...)
Short for "quitting", "exiting", typically from a chat room or online game. Can also be used to greet off another person who is quitting, and is oft acknowledged as a substitute for "bye", "l8r", "cu".
Him: g2g, q
(he leaves, you stay)
Meaning "yes", "affirmative", "true". 0, OTOH, means "no".
Him: Are you listening to me?
Him: Do you understand me?
Him: Is that really so?
Him: You've got to be kidding!?