A person who brings their guitar to a house party, gets drunk, then proceeds to play said guitar in order to try and impress someone. This person is usually a gigantic douche and should be treated with a slap to the face and removal of guitar privileges.
Person 1: Dude, did you see Alex last night?
Person 2: Yeah, he was being such a guitar douche, it amazes me how he has friends.
A douchebag, usually a freshmen, who brings his guitar to school even though he sucks and can play one song (most likely the beginning to stairway to heaven). Said person for some fucking reason get's tons of attention and popularity because he's "a guitar player" always completely frowned upon by people who can actually play guitar. This can also be a "Beach guitar douche", "Camp guitar douche" "Mall guitar douche" etc.
Dude Michael, you see that fucking guitar douche over there? Why are there so many at school today, he fucking sucks so bad!