Happy Girl Meets a Monster (also known as "Beautiful Day") is a classic Muppet routine that has been performed on a number of variety shows.
It was first performed on Today on March 26, 1963, and featured Sue and Sneegle; originally created the previous year for a series of unaired traffic safety commercials. The sketch was later reworked, with Little Girl Sue and Beautiful Day Monster (named after this sketch) filling their place, and was performed on The Tonight Show on October 29, 1968, and The Ed Sullivan Show on May 11, 1969. It was later adapted for use on The Muppet Show in episode 209, with Madeline Kahn and Doglion.
In the sketch, a female Muppet is enjoying a beautiful day outside when a mean monster arrives to spoil it. With a wave of his hand and a few grunts, he makes dark storm clouds appear, but the optimistic girl says that she likes rainy days as well. The monster proceeds to do whatever he can to ruin everything that the girl perceives to be beautiful. The girl tells him that he's awful -- but he's so awful that actually he's beautiful; a perfect example of beautiful awfulness. Embarrassed and upset, the monster begins to shrink. When the monster is small enough, the girl smacks the monster with a flyswatter and walks off.