The hilarious duo performed a perfectly pointless and utterly foul policeman skit on the late-night TV show, which Fallon introduced to his audience as a throwback of an old show they used to star in together, Point Pleasant Police Department.
Playing the roles of Pete and Parker (there's a lot of Ps here — you'll find out why later!), the coffee-swilling, pumpkin-pie-eating police officers do little else but talk to each other, face to face, while spitting over each others' faces and uniforms.
In the first clip, Gyllenhaal and Fallon fire mouthfuls of coffee and crackers over each other. But as the skit continues, the available food ammunition gets more and more extreme.
"I've had some pretty intense roles, but this was the most intense," Gyllenhaal, 35, admits in a momentary break from spitting.
Every time a p-word is uttered, the policemen fire the contents of their mouths into the other one's face. A particular high (or low) point is the moment that Fallon, 41, manages to get a lump of sweet potato pie lodged right against Gyllenhaal's eyebrow, and the duo collapse into unstoppable giggles.
Watch the whole extravaganza in the video above — and be warned: by the end, Gyllenhaal is chugging prosecco out of the bottle , and it isn't pretty!
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