It all went down on the 'Tonight Show Starring Jimmy Fallon' last night (May 22). Actor-comedian Will Ferrell and Red Hot Chili Peppers stickman Chad Smith faced off in an epic drum battle, and a big highlight came when the rest of the Chili Peppers jumped onstage and joined the combatants for a surprise performance.

Prior to the drum-offf, Smith and Ferrell (dressed exactly alike in matching KISS t-shirts and backward baseball caps) participated in a hilarious interview in which the the RHCP drummer pretended to be the comedic actor and vice versa. Ferrell was particularly funny speaking as Smith. When Fallon asked Ferrell (as Smith) about the charity he was supporting, Ferrell (as Smith) replied that the object of the charity was to take instruments away from children (when in fact the Little Kids Rock charity's objective is to help put instruments in schools that need them).

Finally, it was time for the battle, with Ferrell (as himself) going first. While the actor wasn't horrible, obviously Smith blew him away with some complex soloing. It got to the point where Ferrell gave up on the drums and busted out the cowbell. And when he started reprising his classic part in the 'Saturday Night Live' sketch in which Blue Oyster Cult perform 'Don't Fear the Reaper,' the rest of the Chili Peppers jumped onstage and played the rest of the song with him.

And since all the Chili Peppers made the trip to the 'Tonight Show,' they stuck around and played the Parliament-Funkadelic song 'Standing on the Verge of Getting It On' with the Roots, and also performed 'Give It Away' during the closing credits.

As mentioned, Smith's participation in the drum battle benefited the Little Kids Rock charity, while Ferrell rocked out for the Cancer for College charity.

Check out the drum battle above and the amusing interview below.

Watch the 'Tonight Show' Interview With WIll Ferrell and Chad Smith