Jerry, Elaine, George, and Newman are fixated on a new frozen yogurt shop in which Kramer has invested. They are delighted by the fact that the yogurt is advertised as non-fat. Kramer notices that Jerry and Elaine have gained weight. They become suspicious that the yogurt may not be non-fat, so they send it to a laboratory for testing.
Jerry accidentally swears near the shop owner's son Matthew, who then starts to swear frequently. Matthew's mother brings him over so that Jerry can explain to him that cursing is wrong. However, Jerry has a cassette tape of a particularly successful ad-libbed set from a comedy show the previous night, and curses at Matthew again when he destroys it.
George runs into his childhood nemesis Lloyd Braun and makes a derisive nudge to Jerry. When Lloyd notices, George pretends that it is an involuntary spasm caused by an injury. George then has to fake the spasm repeatedly in his presence. Lloyd refers him to a doctor, who concludes that George is faking it. As he leaves the doctor's office, George bumps his elbow on the desk and experiences a real spasm, which worries him.
Elaine starts dating Lloyd, who works as an aide to the mayor of New York City David Dinkins, who is running for re-election against Rudy Giuliani. Elaine suggests an idea for everyone in New York to wear name tags in public, but the date ends badly when Elaine, due to her weight gain from the frozen yogurt, later breaks a chair. After three days without a phone call, Elaine learns from Kramer and a news report that the name tag idea has damaged Dinkins' campaign, and Lloyd was fired for it.
Kramer dates one of the lab technicians, despite Jerry's fears that such a relationship might interfere with the test's results. They make out at the lab after hours, and unknowingly knock a sample of blood into a test tube of Giuliani's blood. This causes Giuliani's results to show he has a high level of cholesterol, to which Giuliani, at a press conference, instead attributes to the supposedly non-fat frozen yogurt. When the lab results show that the yogurt does, indeed, contain fat, Jerry phones Giuliani's headquarters with the tip, and in a following press conference, the prospective mayor promises a crackdown on false advertising. The issue ignites voters, and Giuliani wins the election. When Jerry's local frozen yogurt shop switches to real non-fat yogurt, it tastes awful and business plummets. Matthew curses at Jerry for ruining his father's business.