1x21 - Dennis the Menace

Dennis is blasted by a "strength ray" that Peebee has invented, and suddenly has super muscles. he goes around using his new-found strength to do various good deeds; rescuing kittens from tall trees, etc. Dennis challenges the town bully to a fight, not realizing that his super strength has worn off. But the bully proves to be a coward, and runs off anyway.