When Ben gets in the way of Hex's quest for the "Titan Gauntlets" at a flea market, Ben and Gwen's bodies are switched, putting the Omnitrix in the hands of Gwen.
Tropes in this episode:
- Early-Bird Cameo: We see a girl buying Hex’s spell book at the end of the episode, revealed in season 2 to be Charmcaster.
- "Freaky Friday" Flip: As indicated by the title, Ben and Gwen swap bodies.
- Mythology Gag: Ben and Gwen’s initial dialogue after the switch is the same as the classic episode A Change of Face.
- Voices Are Mental: Ben and Gwen maintain their voices no matter what body they’re in. Gwen’s time as an alien even gets a female voice.
