3rd Rock from the Sun - Season 4 - Eps 10: Two-Faced Dick
After three years, the Big Giant Head has finally accepted Sally's request to have her body changed for a man's. For their convenience, the bodies of Dick and Sally are switched. Now, in each other's bodies, Dick and Sally must try and maintain each other's romantic relationships and get accustomed to the changes that their new gender brings, while waiting for their request to be switched back to be accepted. Meanwhile, Harry is left in charge of Happy Doug's when Doug goes on vacation, but becomes worried when a group of burly, tough-looking bikers arrive.
About 3rd Rock from the Sun

Title: 3rd Rock from the Sun
First Air Date: 1996-01-09
Last Air Date: 2001-05-22
Status: Ended
Rating: 7.5/10 (from 503 votes)
Language: EN
Seasons: 6
Total Episodes: 139
Network: NBC
Genres: Family, Sci-Fi & Fantasy, Comedy, Drama
Production Companies: Carsey-Werner Company
Synopsis
The high commander of an alien expedition lands on Earth -- what he considers to be the least-important planet -- in human form as Dick Solomon. Along for the ride are his alien compatriots Harry, Sally and Tommy -- who is the eldest of the group but is now angrily trapped in a teen's body.
Cast

John Lithgow
Dick Solomon

Kristen Johnston
Sally Solomon

Jane Curtin
Mary Albright

Joseph Gordon-Levitt
Tommy Solomon

Elmarie Wendel
Mamie Dubcek

French Stewart
Harry Solomon

Simbi Khali
Nina Campbell

Wayne Knight
Don Orville