The 42-year-old wasn't initially supposed to strip in the film but said he quickly surrendered to the stripping siren song. The film is directed by Steven Soderbergh and also stars Channing Tatum, Alex Pettyfer and Joe Manganiello.
"Soderbergh said in the beginning that if it felt right, I could strip at the end of the movie. I said, 'I gotta dance, man'. I would regret it for the rest of my life if I was in a male stripper movie and didn't get up there and strip myself," McConaughey said.
The actor will be doing a "wonderfully filthy" dance on the big screen, reported Access Hollywood.
"At first it was scary as hell, but then it became like a drug, and I couldn't wait to do it again. We took a lot of time designing it because the thong's your armor, man. It's your sword. Well, I guess it's really the sheath for the sword," he said.
The film will hit the theaters on June 29.