Kim Kardashian's mum and stepfather have confessed they once shot a sex tape.

The big reveal will feature as part of this weekend's (01Sep13) Keeping Up With the Kardashians episode after Bruce Jenner scolds his stepdaughter Khloe Kardashian for shooting saucy photos for her husband Lamar Odom.

His disapproval soon turns to embarrassment when his wife Kris reveals they once shot a sex tape - just like the one daughter Kim made with ex-boyfriend Ray J.

Jenner says, "I'm all for spicing up a relationship, but in this family... Photos leaking, this and that, look at the problems it's caused."

Bruce then cringes as his wife reveals, "Bruce and I did a video... a sex tape."

The red-faced former Olympian responds, "It wasn't quite a sex tape... but we erased it immediately."