The dog Jerry watches in Seinfeld's episode "The Dog" is named Farfel.
Jerry meets the dog's owner, Gavin Polone, on a flight back to New York. When Gavin becomes ill and the plane makes an emergency landing in Chicago, Jerry is unwillingly left responsible for Farfel. The dog never appears on screen, but its constant barking, destructive behavior, and refusal to cooperate dominate the episode.
Farfel's stay disrupts Jerry's plans, including a movie outing with George and Elaine. Jerry becomes increasingly frustrated by the responsibility of cleaning up after the dog, while Elaine later discovers that caring for Farfel is nearly as unbearable as Jerry claimed. Gavin eventually returns and insists that Farfel is a wonderful pet, despite the chaos.
The name is also a reference to Farfel the Dog, a ventriloquist puppet and advertising character associated with Nestlé's Quik commercials. That cultural reference helps explain why the name sounds unusual. Farfel is not Fido, Spot, or Rex, and the dog is deliberately kept off camera as part of the episode's joke.