girlfriend bomb

When the presence of a girlfriend (either real of fictitious) is introduced by a male during a conversation with a female it is considered dropping a "girlfriend bomb." This is typically done to deter further or perceived pursuit of the male by the female. Either the guy finds the girl he's chatting with unattractive and fears she may be interested in him. Or he's intimidated by her. Thus, he needs to make her aware of "competition", that's he's desirable and taken or that he is *NOT* desperate.

It's basically saying "Hey look...someone likes me OTHER than you!"

When a male you are interested in casually reveals that she has a girlfriend (intentionally or otherwise).

When a male you are casually conversing with mentions within the first five seconds that he has a girlfriend. Not only were your intentions completely civil, but you realize that he is either extremely turned off by you that he feels the need to compensate his repugnance with his martial status, or that his pre-pubescent feelings have gotten the best of him because “sexkitten10” instant messaged him last night.

When a female friend (or otherwise) askes you out and you tell them you have a girlfriend