Dina Lohan played Queen of the Hamptons Saturday night at the 15,000-square-foot Watermill castle of billionaire playboy Ivan Wilzig. In a medieval-style flowing dress, and a flowered veil, Lindsay Lohan‘s mom even had a cadre of identically dressed young ladies-in-waiting who sat at her feet as she held court and flirted with Wilzig, a k a “Sir Ivan,” at his annual regally themed bash. When a young party girl who’d taken the dress code for the fete less seriously passed, Queen Dina barked, “That’s not very medieval!” Later, a Page Six reporter uncovered a hidden gem in the castle: a black room with a large swing chained to the ceiling, a cage with handcuffs, shackles and a slew of giant, stuffed bunnies. It seems the chamber is reserved for anointed subjects. “Only the talent can come in here,” a staffer told us. When we asked where the talent was, he replied they were “coming later.” Egads! Guests at the party included “The Book of Mormon” creators Matt Stone and Trey Parker.