Tricks That Treat - S1.E4

It's almost Halloween. Assuming that Principal Malcolm doesn't know what Halloween is, they offer to teach Creepschool what Halloween is all about by throwing a party for all the monsters. In their search for costumes, the kids come across an armoire full of great costumes they can use for the party. Just after the party starts, a terrible storm breaks out and the lights go out. The guests cry out and when the lights come back on, everyone has vanished except for the four kids.