1) A bag that can contain vaginal discharge.
2) An insult that can be directed to many different groups of people, such as:
a) plain old idiots
b) idiots who think they actually know what they're talking about
c) People whose head are about to explode from their inflated ego
d) People who flaunt their ignorance in an offensive and outright manner.
For the cure to douche baggery please visit youtube, keywords "Cure for Douch Bags"
Jimmy: I'M THE SHIT!!!!
John: . . .Dude, you're such a douche bag . . .