The comedienne stopped by "The Late Show With David Letterman" on Thursday, where she literally stripped down to her spanx.
Check out the video above to see the "Saturday Night Live" alum's hot bod!
"I realized that when you retire, this is it. Like, I'm never gonna wear a fancy dress on a talk show again," she told Letterman. "First of all, it's very hard work. I don't know if you're aware of the contraptions under here. It's almost medical."
Fey continued to discuss her wardrobe with the late night host ... just before taking it all off to gift David with her stunning blue dress.
"I dress up like this out of respect for you. I really do," the 44-year-old explained. "But this is it. Am I gonna put a dress on for Jimmy [Fallon]? That's creepy. He's like my brother. I'm gonna wear special underwear for James Corden? That's not gonna happen."
"Because this is my last time wearing a fancy dress on a talk show and conforming to gender norms out of respect for you, my gift to you is, I want to give you the dress," she added, before slipping off her ensemble.
Needless to say, the 68-year-old was a little more than surprised to see the "30 Rock" actress only in her body-hugging shapewear!
What do you think about Tina's bold gesture? Tell toofab in the comment section below and check out the gallery to see more sexy stars!