Like how Batman sleeps hanging upside down from a horizontal pole... the man hangs upside down at an 180 degree angle while the woman wraps her legs around him and they have sex while at their bodies make a perfect 90 degree angle.
Alfred: You gunna use The Batcave on that chick tonight?
Bruce: Maybe, it depends how my abs are feeling.
Alfred: Well, just whip out the 'ol Bat-a-wang and show her what's up!
A Kink Cave is a place you take especially crazy chicks you wanna bang so they don't know where you actually live. Usually a friends pad or your mom's house if your a really big asshole.
Usually used in cases where the girl is hella crazy and you don't trust her not to hunt you down and kill you, yet you really wanna get it in.
Person 1: Dude, I'm going out to the club and Ima get sum crazy chicks. Can I use your pad?
Person 2: Sure dawg, but if i find semen on the ceiling again im never letting you use my house as your Kink Cave again.
Person 1: Haha, aight. Thanks dawg.