Though I never saw the show, I saw this on a special called 100 most memorable TV moments.
It had actress Diane Muldaur as a acharacter named Rosaland. She was talking to another character casually, the elevator doors open. She steps in...and there's no elevator. She falls to her death.
As they said she wast the bitch character for the show that season, and how funny her character's reaction to it was, it just made me laugh despite never watching that series.