Jon Hamm has likened filming sex scenes with being caught in the rain.

The actor had to strip down with his Bridesmaids co-star Kristen Wiig which he called "awkward".

But the Mad Men star told Playboy magazine that he has come up with the perfect analogy to explain what it is like to get naked with someone who is not your partner.

"It's like running in the rain," he told the adult publication. "There's a certain point where you go, F**k it, I'm already wet. I'm not going to get any less wet so I might as well enjoy how this feels.'

"I mean sure, there's an awkwardness about being in a weird flesh-coloured thong, bouncing on top of an actress.

"And I am not a small human being. I weigh at least 200 pounds and I'm six-foot-two. And Wiig is a twig; she's a skinny little thing.

"I told her, Just punch me in the side if I'm hurting you.' It's weird and uncomfortable at first but then all the awkwardness melts away and you think, All right, we're doing this, so let's have fun with it.'"