Laverne & Shirley S02E10 - Christmas Eve at the Booby Hatch (aka Oh, Hear the Angel Voices)

Carmine calls the gang together at the Pizzabowl and asks them all if they're willing to help him put on a Christmas show for the local hospital. Carmine and none of the others know that it's a mental hospital. When they get there they're greeted by one of the patients pretending to be a doctor. The real doctor enters and tells the group that it is a mental hospital. Shirley immediately becomes anxious as her parents always used to threaten her when she was a little girl that she would be placed in such a place along with her dotty aunt.