I've got to go with my boy, Homer "No brain, no pain" Simpson. Nobody takes a beating like that.
Peter's wife is the one for the medal in a barfight. He did great against that chicken though, but we're talking a room full of chickens here.
Mighty mouse gets smothered in a shotglass of Jack after some chick makes him spaghetti in the front of her pants (what the hell was that about anyway?)
Popeye can't start kickin all that ass unless his girl or little boy is in danger. He's self-less like that, content to take a beating.
Underdog...well, nobody else mentioned him for some unknown reason.
Nobody can drink like Fred. He'd probably be smart enough to take off to the hottie at home. I mean come on, she meaks him brontosaurus ribs like every night.
Bugs Bunny...I don't think he'd do to hot in a barroom brawl. He'd make some good strategic moves, then make a smart aleck comment - when underdog of all people puts him down with a well-aimed juke box.