Filming the latest episode of entertainment show Surprise Surprise, the This Morning and Dancing on Ice host thought she was reuniting a charity worker, Annabel, with boyfriend Richard (played by Ant).
But it’s never that simple with Ant and Dec, both 38, and Holly revealed that she nearly vomited when it all started to go wrong.
The 33-year-old presenter went on to add: “As far as I was aware we had a relatively simple surprise, a boyfriend proposing to his girlfriend, but it all went wrong. I felt my heart sink when she said no. You never think anyone would say no!”
Ant and Dec are known for their pranks but Holly has warned the boys to keep their eyes open.
She added: “The boys best beware, I like a prank so may just have something up my sleeve!”
Saturday Night Takeaway is now on its 11th successful series on ITV and previous pranks include Gordon Ramsay, Simon Cowell, and One Direction.