Some loser who's griping about his bad day at work, and the fact no one respects him there and at home, a la Rodney Dangerfield, gets rude to another driver. Big mistake: that guy is "The Joker," who hunts down our wimpy "Mr. Collins," who winds up pleading for his life. He promises he'll do whatever The Joker wants him to do, if he won't hurt him.
The Joker tells him, "You just run off to your mundane, meaningless little life and I when I need you, I'll call."
Two years later, on a night Police Commissioner Gordon is being honored, The Joker wants to, uh, let's say, join in the fun. He also decides to cash in the "debt" Mr. Collins owes him. The latter has changed his name and residence but the Joker has kept tabs on who and where he is, and calls him up.
So far, I've enjoyed every episode that featured the Joker and a big part of that is his dialog, full of sarcasm, insults and humor. His female partner here, "Harley Quinn," also has a lot of good lines.
Note: The Joker's bodyguards in here are named "Rocko" and "Henshaw," two guys that were in Sgt. Bilko's platoon way back on TV in the late '50s.