Mouth-dibs is an utterance used to secure "dibs" on the oral cavity of a
female prior to engaging in multi-partner intercourse. It is customary, when running a
train on a girl with a questionable sexual
history, for a participant to call "mouth-dibs", thereby mitigating their personal risk of contracting a venereal disease as a result of the escapade.
Bob "Hey, Sally wants us to come over and put her in some finger-cuffs later!!"
Stan " I guess, dude, but I call "mouth-dibs" on that bitch......I
don't like the way her resume reads!!"