Commonly known as a bubble butt; a perfect full ass, very round and resembling a bubble. Also defined as bulging and very bodacious. BB's are always very hot, and very appreciated by the male culture.
A trendy little term of endearment that the self proclaimed 'scene kids' seem to end every sentence with. Could be short for 'baby', could be pronounced 'beebee'. Either way, it's annoying as fuck.