Will Poulter has said his prosthetic testicle in We're The Millers was so lifelike he had to remind himself it wasn't real.
In one scene Will's character Kenny is bitten on the testicle by a spider and he admitted the hugely swollen prosthetic turned his stomach.
Will, 20, said: "Looking down at a testicle the size of a football, you have to try and remind yourself that's not yours. When it's so close you can barely look at it. Everyone was like, 'Oh my God, I couldn't look at it.' I was like, 'it was attached to me so I couldn't look at it at all.'
"It took about three hours to put on. It was a pretty lengthy prosthetic make-up session with a poor guy called Tony who was tasked with putting it on. I was very glad to be rid of the prosthetic. Oh, me and Tony - very intimate."
Will's character also puts his face in Jennifer's cleavage and kisses her during the film, which he said the former Friends star was very professional about.
He said: "She's so cool and down to earth and willing to collaborate on anything. However awkward or tricky a scene may be, no matter how terrified you may be, she's done it all before and is just so cool about it all.
"So the kissing and the cleavage, anything like that, was something we just laughed through and got it done."
:: We're The Millers, which also stars Emma Roberts, is out in cinemas now.