Steven Tyler Walks Into New Orleans Bar & Jams Out to 'Walk This Way'

Steven Tyler got lured into a bar by a very familiar guitar riff ... prompting him to make an AWESOME surprise performance on Bourbon Street.

It all went down Thursday night at the Famous Door in New Orleans, where Steven was casually strolling past. We're told a bar patron gave the band a heads-up the Aerosmith singer was nearby, and the guitarist ran out and invited him onstage.

The band fired up "Walk This Way" and Steven did what he does.

The crowd loved it, but the band members might have loved it even more. You've gotta see how they all reacted. Kudos to 'em for keeping up with a Rock & Roll Hall of Famer.