Tricky Dick 3rd Rock from the Sun : Season 3 Episode 3

Still bitter after their break-up, Dick and Mary begin a childish prank war against each other to try to prove, ironically, who is the biggest adult in the office. Sally attends yoga classes with Mary, where she begins to take a liking to her instructor (Leigh McCloskey). At home, Tommy and his friends have formed a garage band and are practicing in the garage, while Harry wants desperately to be their roadie.