WATCH: Dueling "Trains" with Ozzy & Yusuf at "Rally to Restore Fear and/or Sanity"

Rock fans received a treat at last Saturday's "Rally to Restore Fear and/or Sanity" in Washington, D.C.  Daily Show host Jon Stewart first introduced Yusuf Islam, formerly Cat Stevens, to sing an acoustic version of his classic "Peace Train" on the side of sanity. 

Get a full recap of the Rally and check out pics of our favorite signs

However, it wasn't long before The Colbert Report host Stephen Colbert interrupted and brought out his ringer, Ozzy Osbourne, to represent fear with a performance of the Black Sabbath hit "Crazy Train."  Ozzy and Yusuf alternately commanded the stage before the performance ground to a halt and the two stood arm-in-arm, waving to the crowd before leaving the stage together.

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