Underbite

[Michiko]

when youre making out with a chick, and you slide your hands down her pants and pinch her [bare ass]. [UNDERBITE]!!! see [the intruder]...

[Sonia]

(in nontechnical use) the projection of the lower teeth beyond the upper.

[Hina Muqadas]

when your [eating pussy] and you get a [mouthful] of [shit]

[Lizzy Liz]

the position of the teeth in which the lower teeth go over the upper teeth when a person bites the teeth together, or the degree to which the lower teeth are in front of the upper teeth