NFL players typically don't wear cups to protect their private areas, despite the fact that they play one of the most violent sports on Earth.

Why?

It's uncomfortable and restrictive when you run, and there's always a risk that it can slide to the side and pinch a sensitive area after a big hit, various New York Giants players told Sam Borden of the New York Times.

There's also an unwritten rule among NFL players that the crotch is off limits, Borden reports, so it's not as dangerous as it seems.

Here are some excellent quotes from Giants players from the thoroughly entertaining NYT article.

Tight end Martellus Bennett:

“In my life, at every level, I have never worn a cup. I don’t know anyone who has. I think most guys like to hang out and be free.”

QB Eli Manning on taking snaps from a center who was wearing a cup:

“He was the center and so he was snapping the ball to me all the time. Having the cup there, it hurt my hand.”

Defensive end Osi Umeniyora on the time he tried a cup:

“I know it’s risky. I just felt like I couldn’t move.”

Defensive lineman Marvin Austin:

“Hey, do you see horses wearing cups? No. They’re running all the time, and so are we.”

Manning again:

“You know, it’s supposed to be centered, obviously. So, if it goes to the side and then you get hit and it presses into. ... ”

Mystery solved.