The Hunger Games: Mockingjay—Part 1 star is the first to admit it, too, and even though she described "singing in front of other people" as her "biggest fear," she hilariously demonstrated her "tone-deaf Amy Winehouse voice" to David Letterman on CBS' Late Show Wednesday.
First, though, the 24-year-old Oscar winner admitted she hated singing "The Hanging Tree" in the movie, joking of the song's title, "That's where I felt like going that morning!"
"I still haven't heard it," she said of the song. "I put my fingers in my ears...I was like, 'Will you guys please get, like, Lorde to really sing it and I'll lip synch?' They said, 'No, it's really [got to be] your voice.' So, I avoid [watching] that scene."
J.Law loathes singing in public, she said, because she's "scarred" from a childhood performance. "I have a mother—a Southern mother—who used to just tell me that I was amazing at everything, and I could do everything, but I can't, and this voice...I had when I was like 8, and so I sang in front of the school 'cause I was lik, 'I can do that! I can do anything!'"
The song? "Have a Holly, Jolly Christmas"—and it was a disaster! "My dad laughed for like the entire week," she said.
With a little coaxing from Dave, though, Jen got into the holiday spirit and sang, even getting the late-night host to join in!
She and Dave didn't just show off their (lack of) vocal skills—they chatted about all kinds of stuff, like being hypochondriacs (Jen needed to know, "Is there a test for that?!") and even some stomach issues (the actress joked to Dave, "I made you wanna cleanse out your bowels?").
Dave's not the only one Jen talks crap with, though. "Josh [Hutcherson] and I were talking about getting colonics together," she said with a laugh. "But we were like, 'Can we get a couples colonic? Like platonic—a platonic colonic?! Do you guys have those?'"