Lady Gaga (Eric Thayer/Reuters)

Tony Bennett helped kick off the 90-minute special with the duet, “Lady is a Tramp.”

Bennett had only kind words for his singing partner, saying “she might become America’s Picasso.”

During an interview portion with Katie Couric, Gaga was willing to talk about everything — except her love life.

In the most shocking moment from the show, Gaga revealed that she posed nude for Bennett at the behest of Annie Leibovitz. The sketch will appear in Vanity Fair:

“I walked in and said, ‘Well Tony here we are,’ ... and I dropped my robe, and I got into position. It was very, very nerve-wracking. I felt shy and thought, ‘It’s Tony Bennett, why am I naked?’”

Showing her more vulnerable side, Mama Monster began to cry when she talked about starting a restaurant with her father, Joe: “It was just always my dad’s dream to own a place. ... And to watch him open up the restaurant of his dreams ... that’s wealth. That’s the dream.”

She also shared a touching story about how her grandparents’s relationship inspired “Edge of Glory.”

Dressed in a retro black hat and yellow coat, Gaga cooked fried turkey and waffles with her “favorite chef in the world,” Art Smith.

Gaga performed “White Christmas” (a cover track off her new holiday EP), “Bad Romance” (using a controversial microphone that to some resembles a part of the male anatomy), “Marry the Night” and a few other songs during the special. Watch these performances below.