Supernatural Season 5 Episode 8 "Changing Channels": Official Synopsis

The Trickster (guest star Richard Speight Jr.) throws Sam (Jared Padalecki) and Dean (Jensen Ackles) into an alternate universe where they are characters in different television series, including a sexy medical show, a Japanese game show, a forensics show, and a sitcom. The brothers realize the only way to get out of this world is to play along and become the characters in the shows. However, Castiel (Misha Collins) appears and warns them this universe is dangerous and they must get out before they become trapped. Charles Beeson directed the episode with teleplay by Jeremy Carver.