4x24 - 3rd Rock from the Sun

Dick is suffering the humiliation of having been demoted from High Commander to Harry's assistant, performing the most menial jobs, while Sally has been promoted to his old role. Tommy is preparing for his high school prom with Alissa, but when the Big Giant Head insists on coming, things start to slide, especially when Vicki, who missed out on her own high school prom, turns up. After ruining the prom for Tommy and Alissa, the Big Giant Head whisks Vicki off to his bachelor pod in space.