Celebs aren't afraid to get sexy when it comes to ad campaigns.

Bar Refaeli lets her body do the talking in a video to promote the new men's collection from her line, under.me, reports The New York Daily News.

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Dressed in skimpy lingerie, actress-turned-mom Megan Fox poses in a set of black and white photos for Emporio Armani Underwear's Spring/Summer ad campaign.

This campaign marks the 26-year-old's second season as Armani's female spokesmodel.

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Rihanna's steamy new ad, part of Armani's new jeans campaign, features the sexy singer in a state of semi-undress.

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H and M's newest ad features David Beckham in nothing more than a pair of tight trunks.

The soccer star gets nearly naked for his new bodywear line.

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Rosie Huntington-Whiteley is goes nude for Burberry.

The British beauty poses in the brand's iconic beige trench coat -- and nothing else! -- in the ad for the new fragrance Burberry Body, reports Fashionista.

Huntington-Whitely posed for the British brand last year, showing off the line's leather jackets and coats.

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Other sexy celeb ads include:

Lady Gaga's ad for her new fragrance, Fame.

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The multi-talented Dita von Teese (she's a model, actress, burlesque dancer and costume designer) strips down to the bare essentials for Von Follies.

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Miranda Kerr, who shot into fame as a Victoria's Secret angel, struts her stuff for Reebok.

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Sports Illustrated swimsuit model Kate Upton flashes her impressive pins for Carl's Jr.

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Model Gisele Bundchen pulls out this stunning pose for Versace.

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