Thousands of fans crowded the National Mall in Washington DC Saturday (October 30) for Jon Stewart and Stephen Colbert's "Rally to Restore Sanity and/or Fear," and the two politician-skewering funnymen trotted out a slew of legends to entertain the crowd.

About midway through the show, which already featured a nearly 40-minute set from John Legend and The Roots, Stewart announced the next performer, Yusuf Islam. The folk icon formerly known as Cat Stevens, hit the stage with an acoustic rendition of "Peace Train." However, instead of letting Yusuf placidly strum along, Colbert stormed the stage, ranting about the song's message of harmony. The satirical pundit then proclaimed, "My train is arriving at the stage now and the conductor has an important announcement to make!"

Colbert did a fine job of busting up the performance, and cleared the way for a surprise appearance from one of rock and roll's greatest show-stoppers: Ozzy Osbourne. Decked out in a black ensemble with his signature colored glasses, the Prince of Darkness screamed as he took the stage and led the band through the metal classic "Crazy Train."

However, before Osbourne could finish, Stewart snatched the mic and reprised the whole interrupting-the-rock-legend-thing, spewing protests like, "I will not get on that train! I am not comfortable on that train!" Stewart commanded Yusuf to start up again with "Peace Train," until Colbert jumped in, saying, "I'm gonna pull the emergency brake on this rainbow, moonbeam choo-choo!" Osbourne and Yusuf went back and forth, volleying metal and folk classics about trains, until both gave up the fight, embraced each other and left the stage.

But the audience wasn't left without a stellar performance from some music legends. Colbert and Stewart paced about, lamenting the lack of singers to belt train-related hits, until a line from the smooth chorus of the O'Jays "Love Train" wafted through the air.

"Is that the sound of Philadelphia?" Stewart wondered.

Colbert queried, "Was that the sweet Philly soul?"

It sure was. The legendary soul group then took the stage in slick white suits, busting easy throwback moves to their 1973 single to the delight of the crowd.

What did you think of the "Rally to Restore Sanity And/Or Fear"? Let us know in the comments!