Terror of the Black Night / Battle of the Bands / Halls of Time

When Billy, Mandy, and Grim go fishing, Eris, the goddess of chaos, gets Billy to help her use the Apple of Discord to create chaos (after her father grounded her). Instead of using the apple, Billy becomes distracted with his own idiotic errands, leading Eris to go insane. In the end, Billy finally decides to start creating chaos, but Eris is already too altered that she runs away.