Dud is the opposite of funster. You can easily ascertain whether someone is fun-loving, maybe a little crazy OR are they the type of person to be, well, a dud. You will find a dud working overtime at his or her cube, whilst the funster is already at happy hour.
Karen to John O who she's never met: "So, John: are you a funster or a dud?"
John O. "Well I guess you'll have to be the judge of that after we meet" - clearly a dud.
Karen: "Okay, I'll hang with Troy, he's the ultimate funster!"
A person who is really lame and extremely uncool. Any thing can be dudly, like a dudly haircut. Duds seem to look like losers. It is hard to explain a dud, but simply you can tell who is or looks like dud by how they look or act.
Max: Hey man, watsup?
Trent: nothing git, look at dat fag mike he got a haircut.
Max: Wow, haha he looks like such a dud.