Stoners all over the world celebrated 4/20 this week, and Jimmy Fallon enlisted help from Brad Paisley to mark the occasion by singing his favorite 420 songs.

The country star took the stage with Fallon's band on the Tonight Show Thursday night to sing some of Fallon's favorite marijuana-related tweets of the day, setting off laughs when the camera panned to Paisley, who appeared to be caught by surprise.

"He's been celebrating all day!" the host quipped as Paisley mugged. Clad in a Rolling Stones T-shirt and his traditional white cowboy hat, the clean-cut country star was an interesting dichotomy to the subject matter as he sang tweets including, "I can't feel my face cuz I'm too high / Ate a brownie / It's 4-20." He also quoted from Seal by turning one of his hits into "I Believe I Am High," and parodied one of his own biggest hits, "Mud on the Tires," which turned into, "Let's set a little bud on fire."

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Fallon even joined Paisley as the Simon to his Garfunkel for a high-minded take on "The Sound of Silence," singing, "Hello dankness my old friend / On my weed I do depend / My alarm is probably beeping / Late to work I'm probably sleeping."

It's an especially funny segment coming from Paisley, who's such a straight arrow that he doesn't even drink. The singer-songwriter and guitarist is a good sport in the video above, ribbing Fallon about the possibility of them recording a duet (we'll give you a hint: it doesn't seem likely).

Paisley has, however, recorded duets with Mick Jagger, John Fogerty and even rapper Timbaland for his new album, Love and War, which he released Friday (April 21). He has just dropped a retro '80s-themed video for the album's current single, "Last Time for Everything." He also collaborated posthumously with Johnny Cash on a song titled "Gold All Over the Ground."

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