You're probably aware at this point that Jimmy Fallon has a tough time keeping it together during sketches. (You've had 22 years to notice since he started at SNL in 1998.)
It's nearly a guarantee that this is going to happen anytime he does "Mad Libs Theater" with a guest on The Tonight Show. This time, he did "Mad Libs Theater" with Jon Hamm and Keri Russell. It was just as hysterical as you might guess from the expression on Fallon's face while he was cracking up.
The sketch asks guests to do a Mad Libs-style fill-in-the-blank. Afterward, the team at the show puts their responses into a script on cue cards, and the guests act out a scene with Fallon based on their responses. It's absurd, stupid, and really damn hilarious. That's especially the case with this new one, because Hamm manages to never break, straight-facing his way through the pre-flight instructions on Aggggh Airlines.
Watch the new segment above, or check out past editions with John Cena, Natalie Portman, or Tom Cruise.