Pearl Jam and Chili Peppers Rock Out to a Neil Young Song [VIDEO]

A recent Pearl Jam show in Brazil got a little crazy and ended up with an impromptu jam session with Pearl Jam and a couple of the boys from Red Hot Chili Peppers.

Chad Smith and Josh Klinghoffer joined Pearl Jam to rock out a cover of Neil Young's "Rockin in the Free World".

Pearl Jam is currently on tour outside the states and return for a August 8th show fittingly in Seattle.  What's your favorite Pearl Jam song?