The Lincoln Lawyer star plays cheeky performer Dallas in the upcoming comedy and in one scene McConaughey is tasked with with wearing only a male thong to cover his modesty.
And in a bid to make the dance look more appealing, the actor admits he and his fellow castmates were asked to get professionally groomed - and the 42 year old confesses the experience was far more painful then he had ever realised.
During an appearance on U.S. programme The Tonight Show With Jay Leno on Tuesday (19Jun12), he said, "Everybody got 'manscaped' to some extent... If you don't have to do it, don't ever do this. It was like 7.30 in the morning, I go down there, we're in Hollywood, and I go to this little place in the strip mall. And the place is called Smile. There's this Russian woman in there, and she's just as formal as you could be. 'In the back, clothes off, lay down, turn over.'
"She's pouring this glue and stuff all over you and you're sitting there and you're giggling and all the sudden she lays something on you and just (rips) and it hurts. It does hurt! And the thing is after every time she waxed off whatever hair she's pulling, she says, 'So sorry, so sorry, so sorry.' So you just giggle through the tears and hope you only got to do it once."