Marc Jacobs bares (almost) all in the September issue of Harper's Bazaar. Photo courtesy of Harper's Bazaar

Marc Jacobs knows clothes, but that doesn't mean he has to wear them, OK?

The designer strips off in a revealing new interview with Calvin Klein for the September issue of Harper's Bazaar.

Covered only by a well-placed bathrobe in the Nan Goldin-shot image, Jacobs opens up about his nude Bang fragrance ad, his desire to create wearable fashions, and his body image.

"When guys started looking at me and asking me out on dates, I felt way better about myself," he tells Klein.

"So it was hard to keep my clothes on, actually. And whenever I was asked to take my clothes off, I was like, 'Sure! I haven't worked out for three years to keep this all under wraps.'"

Don't let us stop you. We're still mopping up the drool from that Bang ad.

"I did feel good about the way I looked, so it was easy and -- well, a guy looks better to me with no clothes on than with clothes," Jacobs says of the shoot.

Fair enough. But when it comes to his clients -- which may soon extend to plus-size gals -- Jacobs seems grounded in reality.

"I'm not interested in making stuff for museums; I want the clothes to be worn," he says.

"I don't care if the girl sits on a curb in them after a party and they're destroyed.

"I have to believe that there's going to be a life for these things. Otherwise, I wouldn't send them down the catwalk."

Word. But trust us, MJ -- if we wear one of your designs and it gets destroyed, we'll care enough for the both of us.

Meanwhile, check out Harper's Bazaar's "killer" Rachel Zoe spread.