Definitions by nate fingerman

underbite 

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

i gave my roommate's mom the underbite last night.

underbite by nate fingerman July 17, 2006

intruder 

1. while making out with a chick, you slide your hands down her pants and put your digits in her vagina.

2. reverse underbite with penetration.

my date was going bad until i gave her the intruder. bitch was loving it, yo.

intruder by nate fingerman July 17, 2006