Checking out a chicks ass, specifically while on an escalator or similar situation (so you are 'following' it). Also, can include the act of positioning yourself just behind a chick on the escalator (following close).
Johnny was tailgazing all the way up the escalator at Wheaton, did you see the chick standing in front of him?
The act of following entirely too closely while hiking down a trail, resulting in numerous flat tire's to the back of the lead hiker's boots and increased stress overall for the group
"Ben's an asshole - he trailgates the shit out of me all the time. I started hanging on to nearby limbs when I was lead hiking to spring-load those fuckers and wipe him off his feet if he was too close behind me. Damn trailgating SOB"
Ruler of Lake Titicaca. Rumored to have a bunghole that gets very angry if it does not receive toilet paper. Cornholio the Great is often seen walking around with his shirt over his head and his hands in the air, chanting songs about his power, and his bunghole.
"I am Cornholio! You do not want to face the wrath of my bunghole, for I need TP!"
Butthead: Shut up, Beavis! (uh huh huh huh)
Beavis: Um, okay. (heh heh heh heh).