Mr. Bumpy is a small green, purple-warted monster living under the bed of a ten-year-old boy, where he eats dirty socks and dust bunnies as if they were delicacies. His best friends are Squishington, a blue monster that lived in the bathroom's toilet tank; and Molly Coddle, a Frankenstein's monster-like rag doll belonging to the boy's sister who acts as the straight man to the other's crazy antics. Other characters include Destructo, the boy's toy robot who sees himself as a cop and persecutes Mr. Bumpy for his actions. There's also the Closet Monster, who's made up of the boy's pile of clothes and chases after Mr. Bumpy.