And it's pretty great.
Equal parts fun and surreal, the pair give about a minute and a half of a dialogue-free musical interlude that seems like it may have taken longer than you'd expect to practice.
EDIT: Nevermind that practice thing.
Check it out below.
The Flash has just one more episode -- Tuesday's "The Man in the Yellow Suit," whom many believe to be Cavanagh's character -- before they go on their holiday break and come back in 2015. Catch it December 9 at 8 p.m. ET/PT on the CW.