Gerard Butler says he physically "scarred" Hilary Swank on "P.S. I Love You" set

Gerard Butler and Hilary Swank had what sounds like a pretty traumatic experience while filming 2007's P.S. I Love You.

Gerard set out with some lovely intentions, but things absolutely did not go as planned.

During a recent appearance on The Drew Barrymore Show, the actor recalled: "In this movie I remember saying to the director, 'I'm not gonna think about myself in this movie, I'm only gonna think about her. Make sure she's OK, she's cool,' because that's kinda who this guy was."

And although Gerard obviously did his best to make sure everything went smoothly for Hilary, there was a really unfortunate incident one day on set.

"She's so cool and so great to work with that I almost killed her," Gerard said ominously.

He explained: "You know the scene where I'm dancing and I have the — what do you call them, suspenders? And I literally shot that scene for a day and a half, and I had to dance like an idiot in the suspenders, and it was like that first moment in 300, you're like, 'I can't believe I'm doing this dance in my boxer shorts.'

"And then at one point, the clip, which was a crocodile clip, got stuck in the television as I'm crawling towards her and she's right in front of me and she's laughing hysterically."

He continued: "The camera people had these plastic fronts to protect themselves from this crocodile, it was so dangerous, because I had to ping it and it would go past my face, and this time I'm crawling towards the bed, it gets stuck, it releases — boom! — flies over my head, hits her in the head, slashes her head."

Apparently, it was quite a serious cut, because Hilary had to go to hospital after this happened.

"I mean, I cut her up, you could even see the teeth a bit," Gerard said.

"She has to get taken to the hospital.

"Literally imagine the studio and, in three seconds, everybody's gone, and I'm just sitting there in my Irish... boxer shorts and my boots and a pair of socks, and I just started crying.

"Scarred Hilary Swank, almost took her eye out, and I've just made a fool of myself for two days. This is all I have to show for it!"

Drew and her audience all thought it was hilarious, so that's at least one positive. And Hilary luckily hasn't held a grudge either; after all, this wasn't Gerard's fault, of course.