The Grim Adventures Of Billy and Mandy Episode 13 - Little Rock of Horrors / Dream a Little Dream >Billy, Mandy, and Grim eat moldy pizza leftovers and after falling asleep, they have nightmares. Billy dreams of cute bunnies which turn into horrific and deadly monsters; Grim dreams of an endless number of bossy Mandys; Mandy dreams of being pulled into a volcano and then commanding demons at the rhythm of music, in a scene that reminisces the Night on Bald Mountain segment of Fantasia. In the end, Mandy reveals that her dream was actually very pleasant and she eats the last slice of the rotten pizza.