Billy & Mandy's Jacked-Up Halloween Billy, Mandy, and Grim go trick-or-treating for Halloween, but Irwin is left behind because he needs a scarier costume. After pulling a trick on an old lady, and getting some candies, Grim tells the story of why people pull pranks, which he was partially responsible for. He tells about Jack (voiced by Wayne Knight), a prankster of the old Endsville who just never knew when to stop. One day, the citizens decided to punish him for his constant pranks, and they pulled a prank on the queen, but signed it "From: Jack"; in consequence, the angry queen sent a knight to kill Jack. When Grim went for Jack's soul, Jack stole his scythe...