Shut it down! Molly Shannon and Denis Leary stopped by The Tonight Show on Tuesday, June 9, and pulled off an amazing round of Nonsense Karaoke with host Jimmy Fallon.

"We're about to do some karaoke, but this is no ordinary karaoke, this is Nonsense Karaoke," Fallon, 40, began. "Me and my guests will take turns singing well-known songs, but here's the catch — all of the lyrics have been replaced with odd and unusual sentences, basically nonsense, hence the name Nonsense Karaoke." 

Shannon, 50, who was on the show to promote her new movie, Me and Earl and the Dying Girl, kicked things off with her own nonsense interpretation of TLC's "Waterfalls." The Saturday Night Live alum busted out a few moves that would make Mary Katherine Gallagher proud before interpreting the chorus line as "Don't throw Jason's Barbie dolls."

"My bony cousin shaved a strip of his leg hair / with a butter knife he found in a hutch," Shannon belted. "If a little mime spits in a can, I'll be shy and cry / But it's time to legalize the burgers of lunch."

The hilarious actress then passed the mic off to Leary, 57, who performed a wild rendition of Def Leppard's "Pour Some Sugar On Me." 

"Ask your sister for peas / In a baseball glove," the Rescue Me star crooned. "Play some Boggle with Jeeves / And his hairless pug / Your son Trevor loves quiche / With Dorito crumbs / I'm Todd, Ricky's niece / And I love petting geese, yeah!" 

Leary and Shannon then teamed up with Fallon for a nonsense performance of Ed Sheeran's hit single "Thinking Out Loud." Watch the three stars sing about Snooki's barn and Barney's frog in the video above!