The 'So Macho' singer, who dated the Oscar-winning Hollywood actor during the 1980s, was quizzed by campmates about the pair's relationship.
When model Emily Scott asked how Pitt looked naked, Sinitta said: "Hot. He was beautiful with the most amazing body. I saw him for two years."
She went on: "He was fun, he was young and very sweet. Some ardent fan gave me a slap when I came out of a supermarket over that relationship!
"It was before he made Thelma & Louise but even I saw that movie and thought, 'Oh my god, what have I done?!'"
Meanwhile, McFly's Dougie Poynter asked her to rate Simon Cowell's bedroom performance against Pitt's, but Sinitta remained coy.
Poynter, offering his own opinion on the matter, guessed: "I reckon Simon's sex life is too organised - it will be like, 'It is five past ten, we must have sex for seven minutes darling', then afterwards it will be, 'That was shocking!'"
I'm a Celebrity...Get Me Out of Here! continues tonight at 8.30pm on ITV1, having had a night off due to football coverage.