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Gib Tits is a short acronym for the description of a female's breasts that look good in a bra, but once removed for the bra, they tend to sag, or form a cone or misform. Very much a turn off to most males.

Women who have gross looking breast, tend to wear bras that hide the fact they have nasty, saggy tits that only look "good in a bra" and leading their unsuspecting male mate to believe they "scored" with a hottie.
dude, that chick i fucked last night had total gib tits, i was like "damn, look at that rack", then she took off her bra and i threw up on her face.

She sure has some gib tits.
by Mike d roy February 05, 2011