When a girl looks good far away and gradually gets uglier as she approaches closer and closer. see synonym Block or more
Derived from "Limit" behaviors in Calculus.
(Guy A and Guy B are driving down the strip)
Guy A: Damn, look at that chick over there. She is Bangin!
Guy B: Wow! You are right. She is hot.
Guy A: OMG, dude. WTF is wrong with her eyes.
Guy B: FUCK! That bitch is a limit rule.