On "Seinfeld," Jerry's dentist accused of converting to Judaism just to tell Jewish jokes is Tim Whatley. Bryan Cranston plays Whatley in the season-eight episode "The Yada Yada," where Jerry suspects the conversion was motivated by access to Jewish humor.
Tim Whatley has appeared earlier in the series, but this episode makes his conversion the center of Jerry's storyline. Jerry tells a priest that Whatley has just converted and is already making Jewish-themed jokes. He says he is offended not as a Jew, but as a comedian, a distinction that captures the show's deliberately absurd approach to religious and social sensitivity.
The conflict escalates after Jerry tells a dentist joke that reaches Whatley through the priest. Whatley takes revenge by deliberately prolonging Jerry's uncomfortable dental procedure. Kramer then labels Jerry a "rabid anti-dentite," creating another recurring joke about imagined discrimination against dentists.
"The Yada Yada" aired on April 24, 1997, as the 19th episode of season eight. It is also known for popularizing the phrase "yada yada yada," although that expression existed before the episode and was not invented by the show.