Wormy Gras is the biggest worm holiday there is; where worms all over the world celebrate the joys of worminess. Festivities include dressing up in costumes and taking part in a parade with Dixieland band music.

The holiday was celebrated on Sesame Street in Episode 3856; Slimey spends most of his day before the parade deciding what to wear, finally settling on a grouch costume. Other worm costumes included a straw for an ice cream float, Carmen Miranda, Barney the Dinosaur, a hot dog and the Wormettes. The holiday is a spoof of Mardi Gras, a popular holiday celebrated in New Orleans, Louisiana.