The area underneath a large set of breasts that accumulates sweat and odor, much like arm pits.
That girl had a nasty case of sweaty, smelly tit pits!
The underside of large tits. Functioning much like an armpit, the meeting of two layers of skin forms a crevice or pit, capable of accumulating sweat. Fortunately, tit pits are generally not hairy.
This double D bra is cotton lined, to wick away sweat from your tit pits.