Invited to chair a fundraising benefit at the Toronto film festival she endeared herself to the stellar crowd attending by spontaneously putting herself up for auction.
Her generous gesture came at a gala for the amFar Aids organisation when a one-week ski trip at an exclusive resort was put up for auction.
Seconds after announcing the starting bid of £22,000, the auctioneer jokingly asked the crowd if he'd heard £25,000, "Or were you scratching your nose?" Then there was a pause and the whispers grew louder.
Eventually, one cheeky bidder declared that he would be willing to pay £85,000– but only if the Duchess went along. Sarah gamely promised that she would and the lot was duly sold.
The flame-haired royal is in Toronto for the premiere of the film she produced - Young Victoria, starring Emily Blunt.
Sarah – who has spoken of how "cool" it would be to win an Oscar – has already begun making contacts on the festival circuit.
Her co-chair at Wednesday's bash was Crouching Tiger, Hidden Dragon actress Michelle Yeoh (pictured above) and she also met up with British hunk Clive Owen at another party.