The Contest - S4-E11
Trivia: While appearing alongside Jerry Seinfeld on The Tonight Show with Jay Leno, JFK Jr. revealed that people would constantly bring up his appearance in this episode, even though he never actually appeared in it and was only referenced.
Answer: The name is Delores. He shouts that name at the end of the episode. Then in a later episode, "The Foundation", he runs into her. And he repeatedly calls her Delores.