A pharse satnding for "what the fuck, man?" Usually used when an individual is intoxicated and his friends are talking to him. It tells your friends that you are to intoxicated to follow what they are saying.
Jay: Hey, wanna go get something to eat, Dennys, Mc donalds?
Jack: ......wtf man......?
Jay: Oh...never mind then...
A simile/idiom similar in meaning to "one man's trash is another man's treasure" only, in this case, it means that what is funny to one person may be offensive to someone else.
Tom: "Man, I told this hilarious joke last night. Everyone laughed but Bob. He was a douche and said the joke was offensive."