Similar in nature to a "jackass", but more of a limp-wristed jackass. A prime example of a jabass would be Andy Dick. Absolutely obnoxious, annoying, not funny and flamingly gay.
"Hey man, did you see Andy dick on Conan O'Brien last night?"
"Why would I subject myself to that guy's so-called hilarity. He's a jabass and so are you for liking him."