Battle.net Lingo: Good luck, have fun, and don't die.
Also: gl hf dd
Additional two-letter bits of text may be added in addition to, or in the place of, any of the preceeding abbreviations. They include, but are not limited to:
ka - kick ass
dl - don't leak (for use primarily on Tower Defense maps)
no bs - no backstabbing
Seen as a game is launching, during the five-second countdown.
BNetUser2: boot 3 his slo
BNU1: stfu hes don
Agincourt: gl hf dd
BNU2: STFU U DUMFFUJK