Well aware she'd be a complete wreck in front of Obama, the actress kept her distance when they were both guests on U.S. late night show Jimmy Kimmel Live! in March (15) - but the President insisted on saying hello.

Returning to the show on Monday (20Jul15), the Oscar winner said, "I have this thing when I get nervous, where I get so nervous that I will say something really inappropriate... It's like Tourette's (syndrome) in a weird way... I don't know how to stop it.

"I was really nervous and I was hiding in the back and then somebody from his team came to get me and ushered me over to him. He, like, waited to meet with me and everything had stopped around his world... It was just a lot of pressure."

Obama chatted about how much he liked host Kimmel and how he hoped to reach a younger demographic by appearing on his show, but Theron was stumped for something to say when it was her turn to speak.

She added, "There was this pause and I didn't know what to say and all I could come up with was, 'Well, if you're looking for a different demographic I could take you to a strip club.' It was terrible... He was so gracious and funny and he could tell I was clearly nervous...

"I couldn't sleep for four weeks because every time I closed my eyes, I said, 'Oh my God, I said that! Oh my God, why did I say that?'"