In a picture posted on the GameFAQs forums by AlienNine, of his girlfriend's back tattoo, there appeared to be a boob on the back, slightly below the arm.. Yes, a boob on his girlfriend's BACK. Of course, even the dumbest little 12 year old could figure out that it's fat, but...we JUST don't care. Since that day, the "back boob" has become the new...well, the new "confirm/deny". That easy.

a fatty deposit on the back that hangs in such a way that it resembles a nippleless breast. May sometimes result from a bra that is too tight, causing temporary back boobs. Mostly seen on very fat women or men with manboobs.