Acronym. Orig: Counter-strike, by a player named "Eggroll?"(sic). Said to the losing team in a scrim or match after victory has been acheived, in an effort to brag or boast.
"Good luck with your lives."
Also used in normal conversation as an acronym in place of "gg."
Team leader #1: Final score: 16-3 us.
Team leader #2: damn. gg.
Team leader #1: glwyl noobs.