When did "douche bag" or better yet "douche" become a character description (as in My roommate is sort of a douche). Was it in a literary product, or did it come from the street. When did it happen?

One etymology website cites the first recorded use from the 1951 novel From Here to Eternity. For it to sound natural in a wartime novel implies that it was in use during the war.

However, another refers to a character in the 1939 novel Nine Times Guilty called Jimmy Douchebag and also its inclusion in a 1946 list of wartime slang words.

So, it looks like Wikipedia gets it wrong when they say that the insult originated in the 1960s. It’s pretty old!

This guy says douchebag has become a much more popular insult recently, due to The Daily Show. I kind of doubt this – I seem to remember people using it a lot pre-Jon Stewart.