Can't sleep, clown will eat me

From Wikipedia: Inspired by an event in Simpsons writer Mike Reiss’s childhood, young Bart does not want to give up sleeping in the crib to make way for his newborn sister. Noticing Bart’s affection for Krusty the Clown, Homer decides to build a clown-themed bed to please his son. However, because of Homer’s poor handicraft skills, the bed takes on a sinister appearance and frightens Bart, especially in the darkened room. In his first night in the new bed, far from “laughing himself to sleep”, Bart imagines that the face on the headboard of the bed is coming to life, intoning with sinister glee, “if you should die before you wake…”, before collapsing into evil cackling.

The next morning, Bart is curled up into the fetal position on the floor next to the sofa downstairs, repeatedly uttering the phrase “can’t sleep, clown will eat me…”. The catchphrase inspired the Alice Cooper song “Can’t Sleep, Clowns Will Eat Me” from the 2001 album Dragontown. The phrase has since found its way into popular use.