Theron recalled that Obama said he enjoyed being on Kimmel's show because he reaches a younger audience. The Mad Max: Fury Road star then blurted out, "Well, if you're looking for a different demographic, I can take you to a strip club."
Mortified, she added, "I couldn't sleep for four weeks because every time I closed my eyes, I went 'Agh, oh my god, I said that.'"
Kimmel joked, "If you said that to [former] President Clinton, you would probably still be there."
Apparently, Theron puts her foot in her mouth often when in uncomfortable situations.
"I have this thing when I'm nervous that I will say something really inappropriate and it's like tourettes," she confessed. "I don't know how to stop it. It's like verbal diarrhea. [Obama] waited to meet me. Everything had stopped around his world to meet me and it was just a lot of pressure."
Theron -- who recently broke up with Sean Penn -- said Obama handled their interaction like a pro. "He was so gracious and funny," she continued. "And you could tell I was really nervous and he was nothing but lovely."
ET caught up with the Oscar winner at the Dark Places press junket and she couldn't help but joke about her character's "Justin Bieber" hair in the film. Check it out: