After Billy wakes up from another nightmare involving clowns, he is more terrified than ever towards them, so Mandy and Grim try to cure him of this clown-a-phobia. First, Mandy asks Grim to bring to life a clown's head made on paper mache to entertain Billy, but the spell apparently doesn't work. Then, they dress up as clowns in an attempt to look harmless. However Grim gets fed up and simply picks him up and starts shaking him, ordering him to stop being afraid of clowns. Going into his happy place he consults with his imaginary "Inner Frat Boy" who changes his feeling from being afraid to being angry at clowns, and attacks them with Grim's scythe. In the end, Billy is apparently cured of his fear, but then the paper mache clown attacks and eats them. Fortunately the clown has a balloon animal body and their perfectly fine, but now they all hate clowns.
Gallery
The image gallery for Attack of the Clowns may be viewed here.
Goofs
Goof picture
When Mandy asks Billy who told him Tangerines keep clowns away, as the tangerine man walks away the sign that says "stay in school or else" the word 'stay' disappears and the font changes so it says, "in school or else."
Video
Billy and Mandy - S4E05 - Attack of the Clowns ~ Complete and Utter Chaos
