The show judge keeps his fellow panellists Paulina Rubio, Demi Lovato and Kelly Rowland, waiting for hours before filming because he is busy getting a "four-hander" rub down from two therapists.
When asked on US talk show 'Late Night with Conan O'Brien' who takes the longest to get ready before the show, Paulina said: "Him for sure. I mean, he takes hours to get ready. And we, the three girls, are waiting, waiting and waiting. Of course, we have to wait for Simon because he is the boss."
Surprised at her revelation, Conan asked Simon: "What are you doing? You wear jeans and a T-shirt."
But he replied: "I do sometimes have a massage before the show ... It's a four-hander, two girls."
However, his female co-stars often get their own back on the music mogul - who is expecting his first child with US socialite Lauren Silverman in February - as he admitted they once tricked him into eating bull's testicles by pretending they were chicken pieces.
He said: "They were very mean to me. In fact, one day they played a trick on me. They were serving lunch ... and [the girls] said it was fried chicken and it turned out to be a bull's testicles."
Paulina also admitted she tried the cow's private parts, but added: "I didn't swallow them and he did."