When you're an actor, filming a sex scene is complicated. From modesty patches to prosthetic genitals, the erotic scenes you see on screen are more like choreographed performances than actual sex. That's why some actors just prefer to keep it real — very real. Robert Pattinson and Chloë Sevigny have both admitted to doing real on-screen sex acts on film — and you won't believe what other actors have done it, too!

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Click through the gallery to see which celebs admitted to having real sex on film.