Seinfeld is a sitcom show created by Jerry Seinfeld and Larry David. The show aired on NBC from 1989 to 1998 lasting nine seasons.
It is referenced in Arrested Development several times.
George says he mistook Saddam Hussein for the 'Soup Nazi' from Seinfeld. ("For British Eyes Only") When the Bluth sons visit Iraq and meet the Saddam Hussein look-alikes, one of them is portrayed by Larry Thomas, the actor who played the Soup Nazi on Seinfeld. ("Exit Strategy")
In "Hand to God," Maggie Lizer prods at Michael that he is "only here for the baby." She pronounces the word "baby" in the same mimicking voice that Elaine (also played by Louis-Dreyfus) used to say the word in Seinfeld when mocking her and Jerry's friends who were new parents.
When the family is trying to decide what to raise money for at the dinner they all take a vote and put a paper into a hat. When George Sr. reads all the choices, one he reads out "Shrinkage. Ha! Someone watched Seinfeld last night." G.O.B. then laughs. ("S.O.B.s")
Michael buys a plane ticket and boards a flight he didn't plan on taking, just to get a magazine that mentions him. Similarly, in the Seinfeld episode "The Airport," George buys a plane ticket and boards a flight he didn't plan on taking, right after buying a magazine with a blurb that mentions him. Also in that episode, the discussion about proper tipping practice is a reference to a common motif on Seinfeld and Curb Your Enthusiasm. ("Flight of the Phoenix")
When George Michael is checking into the hotel, he says he wants one bed, not two, justifying his choice with the phrase "Why give her the option?" This is a reference to the pilot episode of Seinfeld, on which Kramer advises Jerry not to bring a second bed into his apartment for a woman who's staying with him, asking Jerry, "Why even give her an option?" ("It Gets Better")