In the snap, Lawrence's mom is sitting in a chair, innocently cuddled up with a white blanket and a glass of wine in her hand as the sneaky Oscar winner stood behind her, flashing a smirk.
Lawrence told Corden that at the time, her mother had no idea she was actually taking a leak -- but "now she knows!"
"I'm actually peeing in that photo, and she has no idea, no clue," the 26-year-old actress revealed. "I went to pee and my friend got the phone because she knew I was peeing and then we both decided to leave my mom out of it."
When Corden observed that Lawrence had "a very relaxed peeing face," her response was just as hilarious.
"I know how to do it," she said. "I've done it a lot. Many years."
Lawrence was also a guest on Jimmy Kimmel Live! this week, where she got her revenge on her Passengers co-star, Chris Pratt, who's been intentionally cutting her out of the selfies he's been taking during their press tour for the film.
"F**k it, I'm going to do something about it!" Lawrence declared on the show. Hear more on what went down in the video below!