Well, this is a celeb red carpet first!

Lisa Rinna has long been a fan of figure-flattering bandage dresses, but in a new TV spot, she's got a secret hidden beneath her LBD: Depend underwear.

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Appearing in a spot promoting the adult diaper brand's new "Silhouette for Women" line, Rinna, 48, raves about the product's comfort and ease of wear.

"I am a champion for positive self image for women," she says in the ad. "The new silhouette makes a woman feel confident and it's fashionable. It feels great -- and they're so soft." (Watch above)

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Rinna's husband of 15 years, Harry Hamlin -- who also appears in the spot -- claims he can't even tell she's wearing them after he caresses her butt.

"I am wearing an evening gown for God's sake! And you can't tell I have it on. Check out the booty!" Rinna enthuses.

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Participating in the ad campaign in exchange for a $225,000 donation to Dress for Success made by Depend on her behalf, Rinna isn't the first celeb to lend her name to the company.

Football stars DeMarcus Ware, Clay Matthews and Wes Welker all recently appeared in an ad touting the male-targeted Depend Real Fit for Men briefs.

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