Abbreviation for the phrase "goddamn, shit the bed!", most notably used in Tool's progressive metal song "Rosetta Stoned". This abbreviation is uttered when the speaker has suffered a shocking or traumatizing experience, and wishes to express his emotion comparable to soiling one's self.
Abbreviation for "God Damn Son of a Mother Fucking Bitch", the alternative expression to "every road goes somewhere"; to be applied when an individual makes a wrong turn in heavy traffic or misses an exit on the freeway.
GDSOMFB has wider applications than the full phrasing, such as when missing a flight, train, or bus when one is in public and would prefer not to use profanity.
Aw, the last train left half an hour ago! GDSOMFB! GDSOMFB! Looks like we're stuck here for the night.