It's Garry Shandling's Show - Season 3 Episode 3 : What's Happening to Me? 1990

Mayor Tom Bradley is in the audience, but he only likes musicals. So this is a special musical episode with musical numbers, complete with a pianist & singing plumbers! Everyone sings a number, including Garry (a little). Pete & Jackie worry that their son, Grant, is going through a stage. Grant is in love with a girl named Madeline. She wants him to study human anatomy with her. Garry gives Grant advice that it's OK to wait to have sex later. So Madeline & Grant agree to wait a while. At the near end, Mayor Bradley proclaims ""Grant Schumaker Day"" & no school. The show ends in a hoe-down.