In real world terms, "a GOB" is someone who displays the same classless showmanship, such as the lead singer of a pub covers band who thinks he's the greatest thing since Barry White but can't sing to save himself, or a standup commedian who obviously thinks his material is great, when in reality it stinks. Badly.
Kate: Yeah, the lead singer's a freakin' GOB.
Gob: No, I didn't mean for you to yell my name at me. Its what I call a double dipped banana with everything on it.
"Yeah, I totally gobed there."