throughout the series was expressed as the "no hugging, no learning" rule. Also unlike most sitcoms, there are no moments of pathos; the audience is never made to feel sorry for any of the characters. Even Susan's death in "The Invitations" elicits no genuine emotions from anybody in the show. Seinfeld does not shy away from making light of tough topics, from death to illness to disability. The characters are "thirty-something singles with vague identities, no roots, and conscious indifference to morals." Usual conventions were broken, like isolating the characters from the actors playing them and separating the characters' world from that of the actors and audience. One such example is the story arc where the characters promote a TV sitcom series named Jerry. The show within a show, Jerry was much like Seinfeld in that it was "about nothing" and Seinfeld played himself. The fictional Jerry was launched in the Season 4 finale, but unlike Seinfeld, it wasn't picked up as a series. Jerry is one of many examples of metafiction in the show. There are no fewer than 22 fictional movies featured, like Rochelle, Rochelle. Because of these several elements, Seinfeld became the first TV series since Monty Python's Flying Circus to be widely described as postmodern. Seinfeld is an avid Abbott and Costello fan, and has cited The Abbott and Costello Show as an influence on Seinfeld: "Everybody on the show knows I'm a fan. We're always joking about how we do stuff from their show. George and I will often get into a riff that has the rhythm from the old Abbott and Costello shows. And sometimes I'll hit George in the chest the way Abbott would hit Costello." The series includes numerous references to the team. George Costanza's middle name is "Louis," after Costello. "The Old Man" episode features a cantankerous character named "Sid Fields" as a tribute to the landlord on the team's TV show. Kramer's friend is named Mickey Abbott. A copywriter for the J. Peterman catalog is named Eddie Sherman, after the team's longtime agent. In Episode 30, Kramer hears the famous Abbott and Costello line, "His father was a mudder. His mother was a mudder." Catchphrases Many terms were coined, popularized or re-popularized in the series' run and have become part of popular culture, including "Yada, yada, yada", "No soup for you!", "Master of my domain”, and "Not that there's anything