SMS language abbreviation for "god damned beer goggles". It is typically used to convey regret or remorse regarding a poor choice of sexual partner due to the consumption of alcohol. While not entirely a legitimate excuse for hooking up with a 3, it can help a person convince them self that nothing embarrassing or degrading has occurred. Often sent as a reply to a text message sent by a friend mocking your choice of sexual partner the prior evening.
TOM: "the zoo asked if you could drop off that chick you took home last night by 2."
JERRY: "fuck you dude. gdbg..."
TOM: "thats not an excuse. real talk though i'll bring my trailer over in a while to help you out"