Mad Men star Jon Hamm has used an interview with Men's Fitness to tear a strip off Justin Bieber.

The 43-year-old actor, who found fame relatively late in life, held the wayward pop star up as an example of what can go wrong when stardom comes too young.

"Look at Bieber or whoever. You're like, 'What the f**k, man? What are you doing? Why?' There's no one telling those people no, and it's a shame."

He suggested that Biebs needs "a mom or a dad or a really good friend who can say, 'Hey, s**thead!'"

And clearly warming to his theme, he continued: "You see people in the world and you're like, 'Do you know how a washing machine works? Do you know how to wash a dish?'

"Life skills are something we're missing… just s**t you needed to learn in life."

And he used the same interview to complain about the attention given to his - ahem - manhood on the internet.

In an unconfirmed report, Hamm was apparently asked to wear underwear on the set of Mad Men because his habit of going commando was causing issues for the wardrobe department.

Asked about the report, he responded: "Would you want people walking up to you and pointing at your dick? I can't believe I'm still talking about this.

"The fact that I'm painted as this exhibitionist is a little annoying. It's become a meme. Being someone who people want to photograph, you have to open yourself up to the positive and negative. It is what it is. If I get mad at it I'll look like a douchebag. But it's silly.

"But when people feel the freedom to create Tumblr accounts about my c**k, I feel like that wasn't part of the deal... But whatever. I guess it's better than being called out for the opposite."