Now that "Deadpool" is in theaters, fans are learning exactly why the Marvel movie got a hard R rating. Ryan Reynolds recently opened up about his naked fight scene, and now another one of the film's performers has shared a story from the film's production that makes it clear "Deadpool" had to be for mature audiences.

Greg LaSalle, the actor behind the film's CG Colossus' facial movements, opened up about one challenging scene during a chat with ComicBook.com. He revealed that since Colossus vomits instantaneously at the sight of blood, hanging around with Deadpool proved to be a... not a good thing. And, as Colossus' facial actor, LaSalle had to bring those heaves and hurls to life.

"Trying to vomit when you're acting is, physically, an incredibly physically draining thing," said LaSalle. "Unfortunately, since motion capture, like I was saying, you just do the takes, loop and loop and loop. By the time you do 10 vomit sequences, and there aren't that many in the film, but you're doing it over and over again to try and modify that. I actually was almost really vomiting on the cameras, because you're whole body has to get into it to make it look real. You know, you can't pretend to vomit, it'll look like you're pretending to vomit. So, at one point [director Tim Miller] was like, 'Dude, you got to stop, because you're going to pass out and you're going to throw up on the cameras.' That was incredibly physically challenging."

To see queasy Colossus in action, see "Deadpool" -- in theaters now.