There's nothing quite as entertaining as watching actors struggle to stay in character when they're on the verge of a laughing fit, and it's even more hilarious if Jimmy Fallon is involved. When Tom Cruise stopped by The Tonight Show Starring Jimmy Fallon earlier this week, he and the late-night host teamed up for a hysterical round of Mad Lib Theatre that'll leave you in stitches. Tom and Jimmy used answers from their hysterically random game of Mad Libs to fuel the script for a made-up spy movie scene. The two couldn't help but giggle through the entire dramatic skit as they sat on a fictional train together and fired off lines about "the world's most amazing sanitation engineers" and "a ransom of 1,000,256 sofas." Watch the LOL-worthy segment above, and you'll certainly chuckle just as much as they did.