A portmanteau of "bitch" and "douche". It is used alternately to describe either men or women as bitches and/or douches. Derived from a certain individual's surname from a particular boarding school.
A: "I really don't like that new girl. Doesn't she make you think of you-know-who?"
B: "Yeah, I know; she's such a freaken boosh."
A term used in the up and coming sport - Extreme LazyBaseball. It has two meanings, the first is similar to bush in reference to bush league. The second, the much more common use, is a name for a massive home run.
*Marcus Thames hits a home run 500 feet* One fan in the crowd cheers with, "Look at that boosh!"