Biggest Jerk on TC
I'd have to go with the blind guy (jim Walsh) who punched out jack after ruining the dinner with the Ropers...Classic line though

Mr. Roper : I bet you can't wait to see us all?

Walsh: You lose

or maybe the con man who fakes choking in restaurants to get out of paying the bill , and tricks the kids into a free dinner.

even the buddy Jack had who tried to get his restaurant from him. and Angelino thought he was a help to Jack

Any more?