You can read Grantland’s full oral history of Boogie Nights here.

Mark Wahlberg: I show up at this effects house in the Valley. And I have to stand there and take off my clothes. And they start basically sculpting this thing around you. It’s very uncomfortable, very awkward. The first time that they did it, they did the exact same specs/measurements of what they thought John Holmes was like — if anybody doesn’t know who John Holmes is, he was a very famous porn star in the ’70s — and this thing was, like, down past my knee. And literally it was … pretty flaccid. You’d sit down and the thing would bounce up like this.

So the first one did not work. It was not good. Everybody thought it was ridiculous. I had to come out to the set and show everybody. Everybody’s like, “Hey, look at this thing! Check this out, what do you think?” They had to kind of modify it a little bit. It was pretty embarrassing. Then you have this weird guy putting it on you. You have to wear it all day. There’s not a way to go to the bathroom or anything like that.

It’s actually the only prop that I’ve ever kept from a movie. I didn’t think there would be that much interest in it. But maybe at some point I can sell it at auction for charity.