Watch: Jennifer Lawrence and Jimmy Fallon face off in "Box of Lies"

Who's the better liar? Jennifer Lawrence or Jimmy Fallon?

The two faced off in a game of "Box of Lies" on "The Tonight Show Starring Jimmy Fallon" on Thursday. The rules? Each would select a box -- without the other one seeing -- and then say what's in the box. They could either tell the truth or make up its contents, and the other person had to guess if it was a truth or a lie. Sounds pretty simple, right? But in reality, it was pretty hilarious.

Lawrence chose a box and said it contained a Rubik's cube inside Jello, and Fallon picked up one he said contained a Backstreet Boy action figure surrounded by Hershey's Kisses. Were they truths or lies?

Check out the video below to find out. You'll probably chuckle along the way: