Trama

A man in the bar becomes sick of Cliff's obnoxious know-it-all behavior and challenges him to a fight. Will Cliff shut up, accept the challenge, or run away?

Tough guy bar patron, Victor, has taken a dislike to Cliff and his know-it-all attitude. Carla eggs Cliff on to confront Victor, as she says he is just a blow-hard who will back down once Cliff shows he's not afraid of him. Reluctantly Cliff does so, but Victor doesn't back down, wanting to "take things outside". While Victor goes out waiting for Cliff, Cliff sneaks out the Melville's entrance. The next time Cliff comes to the bar, he brings his tough guy colleague from the post office, Lewis, in the off chance that Victor shows up as well, which he does. Knowing that Lewis is there, Cliff verbally pushes Victor more. Lewis defends Cliff until what Victor says about Cliff makes Lewis think that Victor is right. Without his bodyguard, Cliff uses the oldest back down statement in the book: that he knows karate and his hands are lethal weapons. Victor says that he will leave Cliff alone if Cliff admits that he's a loud mouth know-it-all. It's time for Cliff to put up or shut up, Diane the only person in the bar who believes that Cliff will actually put up and display his karate skills. Elsewhere in the bar, Sam is disgusted with Diane, who is making a mockery of the bar's football pool by making her picks based on her own sensibilities, such as cities whose symphonies are led by foreign born conductors. But what bothers Sam more is that she is winning the pools.—Huggo

Cliff is on another rant about this-and-that, and it has grated on the ears of a bar patron named Victor. Victor claims that Cliff is just a blowhard who spouts useless knowledge that has no bearing. Cliff quietly tries to back down, but Carla recommends he stand up for himself. Cliff does so, and Victor suggests they settle their differences with a fight outside. But while Victor goes outside to await Cliff, Cliff sneaks out of the bar through Melville's, and goes home.

The next day, Cliff comes to Cheers with a tall, athletic Postal worker named Lewis. When Cliff sees Victor is at the bar, Cliff provokes him with some more of his know-it-all facts, and Victor once again confronts him. Cliff sends Lewis to fight, but soon Lewis and Victor see eye-to-eye that Cliff is very annoying.Lewis then leaves the bar...and leaves Cliff to face Victor on his own.

With nowhere else to turn to Cliff states that he knows karate, causing Victor to laugh at this claim. Victor then delivers an ultimatum: if Cliff will admit that he's nothing but a big blowhard that spouts useless drivel, he'll leave the bar for good. In response to this, Cliff quietly leaves the bar, with Sam and the others chastising Victor for beating up on Cliff. Victor apologizes, but claims that Cliff just brings out the worst in him, before he leaves the bar too.

Sometime afterward, Cliff returns to the bar with some pieces of wood, and intends to demonstrate to the group that he does know karate. As the group watches, Cliff breaks the pieces and impresses them all! After his demonstration, he then takes Diane aside, and confesses that he doesn't know karate, and needs to go to the emergency room.

Diane covers for Cliff, claiming she needs someone to walk her to her car.