A person who thinks that they are the most knowledgeable source of information on a particular topic when in reality they don't jackshit about it. This person parades around as an expert on subjects, which by sheer nature of their lack of intelligence, prevents them from ever having the slightest expertise of knowledge about the subject.
That Wayne Greene is a realdouche bag because he thinks he knows so much about surgery, when he doesn't even have a medical degree.
Verb: When someone is such a douchebag that they die, go to heaven and then procede to wiggle around in God's Vagina like the stupid cunt sucker he or she is!
Noun: When Someone has reached the limit of douchebaggeryyou may call them this.
Verb: Harry Potter had a douche wiggle this morning and god was never so happy!
Noun: Bob likes to douche wiggle more than is approved by the FDA.
A baseball bat. Specifically an older bat, kept behind the driver's seat for the sole purpose of beating the fuck out of cracker ass douchebag white boys.