Sammi Sweetheart is coming back to the “Jersey Shore.” The news was not only a surprise to fans, but to the cast itself. Sources told TMZ that Pauly, Vinny, Snooki, JWoww and The Situation had no idea Sammi would be showing up to set this past week. Their responses were captured on camera, and will all play out on the second half of “Family Vacation” season 6, which is currently filming. No word on an air date.