Kristen Bell used a dog grooming razor to shave her husband Dax Shepard's butt ahead of his nude movie scene.
The 39-year-old actor was concerned it might look like there was a "werewolf trying to escape" from his derriere when he strips off in film 'This is Where I Leave You'.
So he enlisted the help of his pregnant wife to perform the procedure with an "off-the-shelf electric razor that you would trim your dog with".
He explained: "While I don't have a lot of hair on the cheeks, there's an ample amount ... there's a forest in the valley. "My deep, deep fear would [be that it'd] look like there was a werewolf trying to escape my butt crack.
"So I asked Kristen to help. My wife, the beautiful Kristen Bell, who people already can't understand why she's with me, got the pleasure of ... you know."
However, Dax - who has 19-month-old daughter Lincoln with Kirsten - wasn't expecting the 34-year-old star to enjoy the experience quite so much as she started humming 'Funkytown' by Lipps Inc while she was taking the razor to his rear.
Speaking on 'Conan', he recalled: "She's the only person I would feel comfortable ... I didn't even feel comfortable with her doing it. It was a terrible experience.
"I don't know why, I think she had some nervous energy going on but while she was trimming she was humming, 'You gotta move on now...' "I already felt so vulnerable and weird and then she was singing that song."
As well as feeling apprehensive about Kristen - who is pregnant with the couple's second child - taking the clippers to his butt, Dax admitted he felt nervous about going naked for the movie and tried to ensure his derriere looked in good shape.
He added: "It was incredibly nerve-wracking. I spent a lot of time doing lunges and squats."