A foul smelly, smegma-like excretion found under a womans breasts, between her boobs and her rib cage. Generally caused by sweat build-up through excessive bra wearing and a sad lack of personal hygiene.
John, "My wife wanted me to lick her bra cheese last night."
Billy, "Mate, that's fucken foul. Did you do it?"
John, "Too right mate, after she'd sucked all the smeg off my knob."