(After Farley starts to sing Let a Smile Be Your Umbrella, Oscar interrupts, saying that it really goes like this:) Oscar: Oh, let a frown be your umbrella on a rainy, rainy day. And if your grouchy cries Just tell her that a frown will always pay. Whenever skies are gray Don't worry or fret. A frown will bring the raindrops and you'll always get wet. So let a frown be your umbrella on a rainy, rainy day! (Then, I think, Oscar asks Farley if he understands how the song goes now. Farley says, Yeah, but I'm not sure I like it.)
https://primanota.net/sesame-street/let-a-frown-be-your-umbrella-lyrics.htm