Debbie Downer is a Rachel Dratch sketch. Dratch plays Debbie Downer, a woman who makes negative comments all the time. Whenever Debbie makes one of her signature negative comments, a "wah-wah" sound effect plays, or occasionally, a cat sound if she commented on cats.
The lyrics to her theme song are: "You're enjoying your day, everything's going your way, when along comes Debbie Downer. Always there to tell you 'bout a new disease, a car accident, or killer bees. You beg her to spare you, 'Debbie, please!' but you can't stop Debbie Downer!"