The secret to Christina Hendrick's sexy success on 'Mad Men'? Her underwear "Mad Men" star Christina Hendricks shared her sexy, on-screen secret on "Conan" Thursday night. If you've ever wondered just what the secret behind Christina Hendricks' sexy look on "Mad Men" is, then wonder no more. The woman who brings Joan Holloway to life has revealed that it's all about what she wears underneath those sleek '60s fashions -- era-appropriate underwear. OK, obviously, Hendricks' sexy look has a heck of a lot to do with what she's packing before she ever hits the wardrobe department. But in an interview with Conan O'Brien, she gave plenty of credit to her supportive foundation garments. "Everything is incredibly authentic and meticulous," Hendricks said of the show's clothes. We have the full undergarments and the slips and the thing over that. It's a little bit of work to get dressed. But it's worth the work. After all, those form-fitted under layers are what give Hendricks her on-screen wiggle. You put these things (on) and they sort of make you stand upright and your body just naturally moves a certain way. I always thought that's what made this sort of walk happen -- you put these undergarments on and this tight dress. My husband teases me and says I walk like that at home as well, but I attribute it to the undergarments. See what you think of Hendricks' wardrobe and her walk when "Mad Men" airs Sunday night at 10 p.m. on AMC. Do you think it's really the underclothes that give Hendricks' her sexy look?