She's the brash girl everyone loves to hate on The Hills, but Kristin Cavallari isn't afraid to share her less-than-fabulous moments with

In this exclusive video, Cavallari tells Us about her Thanksgiving plans, her celeb crush ... and her most  embarrassing moment -- period!

"I don't know if this is appropriate," she warns.

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The blush-inducing memory? A photo shoot involving "little booty shorts and lingerie," a bold stylist and a feminine hygiene product.

Curious? Watch the clip above!