"We were both like, 'No, man. No, no, no,'" Kristen tells Ellen about the once-in-a-lifetime opportunity.
"I was on the dance floor...and I was just kind of casually getting into it, and all of a sudden, I see...J.Lo looking like J.Lo, right? So elegant. And then she just [points at me], and I was like, 'Me?!' She gets up, we start dancing together, I'm freaking out. I'm like, 'I'm dancing with J.Lo! I'm dancing with J.Lo!' I'm like hitting her butt. It's amazing. She didn't mind. It was consensual."
That's when Kristen's magical moment with Jenny from the Block came to a halt.
"Then my husband sees," she continued. "And he came over, and he kinda cockblocked me. Sorry, but he did! I'm sure from his perspective, he was like, 'My wife's dancing with J.Lo! That's so cool!'"
Kristen said her hubby entered their circle doing a mortifying dorky shimmy.
"We were both like, 'No, man. No, no, no,'" she said.
Although Kristen admitted that her husband of over four years is actually a great dancer, "He kind of like ruined my vibe."
Ellen also pressed Kristen about "Frozen 2," and although the Disney star was sparing with the details, she did say she's already "recorded the movie."
"I know the songs, I know the story, it's very good," Kristen said. "I can't say much more than that, or I'll get in trouble!"
In honor of Kristen's new film, "Pandas," she and Ellen played the "Act It Out" deck from "Heads Up!" dressed up as the beloved animals.
Watch the hilarious video below.