A deliberatemisspelling of "douche" intended to convey the novice nature of conduct that does not even rise to the level worth of being characterized by the term "douche."
He was so pathetic in his pursuit of her that he couldn't even be branded a douche. No, this novice didn't deserve that moniker. He was simply a plain old doosh.
When a person, is such a douche that spellingthe word traditionally does not begin to describe how much of a douche they are. So, you start adding o 's. The more ''o''s, the bigger the douche.
Brian is becoming a real Douche. Yeah, but Kevin is a fucking Doosh and Matt is a Doooosh.