Mrs. Gunderson

Mrs. Gunderson is a resident of the building and lives on the third floor in apartment 3A. She is a neighbor of Penny, Sheldon and Leonard and lives opposite Mrs. Vartabedian. She is first and only seen in "The Lunar Excitation", (Season 3 - Episode 23). She is never mentioned or seen in any other episode.

When Penny gets drunk and spends the night at Leonard's - due to the two of them making so much noise, Mrs. Gunderson was able to hear them having sex as she lives directly below them. The following morning when Penny heads to work, Leonard follows her down to the third floor and Penny tells him that them sleeping together was a mistake. When Penny leaves, Leonard shouts at her angrilly and accuses her of using him for sex. As he says this, Mrs. Gunderson exits her apartment. Her and Leonard smile at each other and Leonard says good morning. Mrs. Gunderson says good morning as well then jokingly says "or should I say, Yee Ha!" a reference to