Mary-Kate Olsen shocked American audiences during a recent TV appearance - when she persuaded a late night talk-show host to take his clothes off on air.

The former child star made an appearance on Friday's Late Night with Conan O'Brien, when the cheeky host asked for her fashion advice.

And the 22-year-old actress was keen to help him strip off.

Standing up to style O'Brien, Olsen dared, "If you were a woman you could pull of a high-waisted pant. I would take off the tie and the jacket... roll up your sleeves, undo your (collar). And then I would take this shirt off underneath, but then you'd have to really just show it all right now."

Following her instructions, O'Brien lifted his shirt before the red-faced actress added: "You're wearing Calvin Klein briefs now aren't you?"