The Frog is a minor character which appeared in the Bump in the Night episode," Love's Labor Bumped." It is a tiny green bug eyed frog and is used as a visual gag.

In the episode, Mr. Bumpy disguises himself as Molly Coddle as a prank to play on a love sick Destructo. When Destructo notice that the Molly's voice sounds different, Bumpy says he has a throat infection and it feels like he swallowed a frog.   

Then the little green frog appears in Bumpy's throat and leaps out, the frog then lands on the floor and hops away.