Alves, who tied the knot with McConaughey married last month, was secretly looking on as he stripped and paraded around onstage in skimpy underwear to play strip club owner Dallas in the hit movie, reported Daily Star.
"I didn't know she was there. She had sneaked in at the back and I'm glad I didn't know because I would have been even more nervous than I was. But I got it done and she enjoyed it. She gave me the thumbs-up.
"It was nerve-racking to dance in front of everyone live. Then having to strip down was even more nerve-racking. The biggest challenge wasn't the dancing, it was the tiny thong. It's a huge leap of faith to trust a thong and it's your only protection up on stage," he said.