A person who barges into a chain of comments and pretends they were apart of the whole conversation. This person usually adds something completely irrelevant or annoying.
Jane: Hey you want to see a movie friday?
Jill: Sure, what movie?
Jane: I dont know. How about District 9?
Jill: Sure. I heard it was good.
Douche: District 9 sucks. GI Joe was better.
Jane: Go away Douche. You comment crasher.
A person who comments on a post and doesn't feel like their post got enough praise, thus comments again for people to notice them.
Joe Blow is feeling sad
Douche: cuz your gf dumped you? haha.
Jill: Feel better!
Larry: Cheer up dude!
Douche: get a life loser!
Hilary: Wow Douche, screw off you comment attention whore. Where do you find these assholes Joe?