4x20 - The Grim Adventures of Billy and Mandy

After Grim's scythe fails to open a portal, he decides to sharpen it, but the blade breaks. Billy, Mandy and Grim go to the Underworld to meet F (a parody of James Bond's "Q"), who is in charge of the Underworld secret gadgets. F unveils Scythe 2.0, which is a new-and-improved sentient, autonomous, thinking and feeling computerized scythe, that Grim uses while his classic scythe is being repaired. When Mandy tells Grim to do his usual humiliating chores, Grim delegates the work to Scythe 2.0, which rebels and decides to reap by itself, starting with Billy and Mandy. Grim saves the kids, takes Scythe 2.0 back to the Underworld, and returns with his old scythe.