What: The 1978 WKRP in Cincinnati episode "Turkeys Away," which concerns a Thanksgiving Day promotion gone wrong. Here is its famous closing scene.

Why: WKRP was a mild little sitcom set at a Cincinnati radio station which had just undergone a format change to rock music. The old guard (bumbling station manager Arthur Carlson, slimy ad salesman Herb Tarlek, and clueless news director Les Nessman) struggled to mesh with the new generation (smooth program director Andy Travis, shy traffic manager Bailey Quarters, and hip DJs Venus Flytrap and Johnny Fever), all held together by bombshell receptionist Jennifer Marlowe. Seven episodes into the first season, this tension is at its peak, as Mr. Carlson feels he has to assert himself as a manager of his vastly more competent new employees. And so he concocts the greatest Thanksgiving Day promotion ever, keeping the details secret from his staff. What follows is the shining moment of 1970s television comedy, as Nessman uses his Buckeye Newshawk Award-winning abilities to cover… well, I won't spoil it for you, except to say that Mr. Carlson's line before the closing credits may be the greatest in sitcom history. Oh, the humanity.

Impact: Among the provocative sitcoms of the period, WKRP was probably the least confrontational, and thus it never became a cultural touchstone like All in the Family or M*A*S*H. Though the series later got three Emmy nominations, "Turkeys Away" was too far below the radar at the time to get attention. In later years, though, Richard Sanders' delivery as Nessman became the stuff of legend. With the tremendously addictive Hulu now available, everyone can see. (Though with some of the original music missing due to copyright issues. This led to some unfortunate recutting, in this case involving bowdlerizing a scene about Pink Floyd.)

Personal Connection: As a kid, I watched every episode of the first few seasons of WKRP, none more often than this one. This episode taught me the dangers of hybridizing advertising and journalism, something I railed against for years. I've certainly flirted with that line since, though not at the expense of any galliforms.

Other Contenders: Manuel names his "filigree Siberian hamster" after Mr. Fawlty in Fawlty Towers''s "Basil the Rat"; "Polymorph"; Red Dwarf's homage to Alien; and three treatments on the "Fails to Ask" sitcom paradigm—Seinfeld's Jerry fails to ask his date's name in "The Junior Mint", Coupling's Jeff fails to ask how to speak to an Israeli woman in "The Girl with Two Breasts", and the M*A*S*H brass fails to ask if a new surgeon actually exists in "Tuttle".