Means "Bottom of Bag", as in potato chips or fries. Has a contradictory meaning, for B.O.B. chips are delicious according to Jessica, but B.O.B. fries are irritating according to Lynn.
A polite term used by a man to describe a fat girl as it's better than calling them a chunk.
Two mates are having a beer in a pub and a fat girl walks past....
Rich: I don't fancy yours much mate.
Alan: Yeah you're right buddy, she's a B.O.B. - a big old bird!!