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1.
INB
very similar to ANB. when such an unbelievably attractive female comes into sight, even the peripherals, your boxers instantly fill with semen. there is no way to prevent this. like ANB, INB is typically an extremely sarcastic joke for the ugliest women alive.
Oliver: "The floor is shaking, Kimberlyn must be coming"
Mark: "Don't look! You will bust multiple nuts!"
Kevin: "Shit...I couldn't help myself. I just had to look at that fine ass INB."
by WeinerRedeemer December 13, 2009
 
2.
INB
A shortened version of "I'm not bothered."
girl1: ooh look, your ex-boyfriends over there.

girl2: excuse me, INB.
by Livii August 08, 2007