Jurassic Pooch / Organ Grindor / Dimwit Dexter

S1, E5: In `Jurassic Pooch': Dee Dee takes Dexter's dinosaur for a walk, in `Orgon Grindor', Monkey is hypnotised to do evil tasks, and in `Dimwit Dexter', Dexter's brain refuses to work for a math problem.