Doctor Who's Billie Piper says she's been intrigued by swingers' parties.

Oh Billie, Billie, Billie! Sometimes you have to know when to keep things to yourself!
Daily Mail:
Billie Piper's raunchy new role as a high-class prostitute in new drama 'Secret Diary of a Call Girl' has prompted her to confess a few secrets of her own.
The former Doctor Who actress, whose latest role sees her play prostitute Belle du Jour confessed: "I've always been intrigued about swingers' parties."
Dressed to thrill in a skimpy black silk camisole, pencil skirt and stockings, Billie underwent a remarkable makeover to play the call girl, wearing a succession of revealing costumes.