By Meredith Lepore
Oct 04, 2016 @ 9:00 am

Emily Blunt may have some issues when it comes to telling the truth in her new film The Girl on the Train, but she knows exactly what she is doing when lying can be used in a game. She proved this Monday night on The Tonight Show when she played Box of Lies with host Jimmy Fallon.

The premise of the game is simple: A player chooses a box that contains an object—usually a very odd one—that his opponent can't see and can either truthfully describe what is in front of them or lie about it. The other player must then decide if the description was the truth or a lie. "Do you have a strategy at all?" he asked before they started. "Why would I tell you my strategy? That's my strategy, is to not strategize with you," she said.

Blunt kicked things off by going first. She picked a turntable with a pepperoni pizza pie on it, calling it "cute." She decided to say what the "interesting thing," actually was. "It's a record player with a pizza on it," she said. "So you pulled a record player out of the box and it's spinning?" joked Fallon. He accused her of lying only to be proved wrong. "You suck!" the actress said.

Then it was Fallon's turn. He selected Box 3. In Box 3 was another smaller box, also Box 3, and then inside that was an even smaller Box 3. Fallon couldn't stop from laughing as he decided what he would tell Blunt. "In my box, it's another box and inside that box is another box," he said in a slightly funny accent. Blunt somehow fell for it and assumed he was lying only to be told he was actually telling the truth. "It was so boring! They were laughing too [she said pointing to the audience.] Guys, you're easily pleased," she said scolding them.

For the final round, Blunt picked a box with a Hulk action figure dressed as a clown. She decided to tell a lie this time. The mother of two little girls said, "I almost feel like I can't say this having daughters. It is a My Little Pony with a syringe stuck in it. That is wrong," she said. "Well there are rumors of horse steroids going around," said Fallon. Even though she gave a great performance, Fallon knew she was lying and won the game. Watch Blunt play Box of Lies in the video above.

During the show, Blunt also talked about her two young daughters, 2-year-old Hazel and 12-week-old Violet. Their dad is Blunt's husband John Krasinski. The mom said her older daughter has actually been very interested in this new addition to the family instead of ignoring her like some children. The other day Blunt caught Hazel dragging her sister across the wood floor to get "her in a better spot." Blunt said she was very proud that, for a time, that Hazel had inherited her mother's British accent when it came to saying the word "water." But sure enough, the little girl has now got her American accent and says water in a more flat tone. Blunt tried to correct her, but the 2-year-old wasn't going for it. Looks like Dad has some influence, too.

Watch Blunt talk about her children in the clip above.