The 43-year-old Olympus Has Fallen actor said, "It was an afternooner, but it was fun. She is unhinged.
When Glanville, 40, revealed that they had slept together on a Jan. 24 Watch What Happens Live episode, she gave the impression that it had been a little longer than that. Glanville gave him an "11" out of ten for a lover and stated that they "had a little week of fun."
Gerard Butler was informed about Glanville's comments when a paparazzo confronted him as he was walking down a street and reportedly said, "Brandi Glanville says you're great in bed."
"And you know what I said: 'Who's Brandi Glanville?'" Gerard Butler recalled to Stern. "Because one, I didn't know her last name and two, I didn't know she was a celebrity and I didn't know she was going to f–king tell people about it!"
How did he not learn her name? "Here's the thing. You're at a beach party, you're having fun and this girl comes along," he says in his defense. "'So, what do you do?' She says, 'Doesn't matter.' We hung out. We had a little bit of fun."
Once Gerard Butler figured out who she was, he called Glanville up. "I said one, 'I'm not very happy you did that because there are certain things you keep a little private.' And two, 'I'm sorry I said I didn't know who you were!'"
Gerard Butler is now, however, happily off the market. At the after party of the NYC premiere Monday of his new film, Olympus Has Fallen, the actor told Us Weekly why he loves girlfriend Madalina Ghenea, a model/actress he's been dating for 10 months.
"What I love about her is she digs me. Not many people when they get to know me put up with me and she does," he confessed. "She's incredibly beautiful, s*xy, she's very compassionate, super smart and truly, she does get me. That's nice. It's nice when somebody pins you and they know everything about you and they see it in a positive way. A lot of stuff that I don't see in a positive way, after she's pined me I say, maybe I'm all right. Maybe I'm not the biggest dickhead on the planet!"