It's not uncommon for the occasional mishap to occur when guests are invited into a set, but guitar greats Tom Morello and Slash found themselves unknowingly in danger of serious bodily harm while joining Ozzy Osbourne at his 2015 Voodoo Music Experience headline set.

Morello relayed the story to SiriusXM host Howard Stern as seen in the video below. This show in particular was an "Ozzy and Friends" set, with the legendary Black Sabbath vocalist also welcoming Geezer Butler as the other big name during the Halloween performance.

The Rage Against the Machine guitarist starts laying the groundwork for the events to come stating, "It's me and Slash and we're playing in New Orleans with Ozzy ... and we're all coming out to play 'Paranoid' at the end for the big finale. He plays 'Iron Man' and then it says 'Mama I'm Coming Home' on the setlist and then 'Paranoid.' And the crew says, 'He never plays 'Mama I'm Coming Home' so after 'Iron Man' get ready to go out there and rock 'Paranoid.' Got it. So we got our guitars on and he finished 'Iron Man' and Slash and I walk out there and Ozzy goes, 'The next song's called 'Mama I'm Coming Home.'"

According to Morello, he and Slash quickly retreated realizing they weren't supposed to be onstage yet and found a spot at the back of the stage to wait until it was time. But the story doesn't end there.

As Morello tells it to Stern, "There's a crew guy gesticulating wildly. He's apoplectic and I can't hear him because it's super loud and we're like 'What?' He must have been afraid or had been scolded that you can't come across the stage for any reason, but he's trying to convey what's really a very important message to us. So finally, he can't stand it and he runs over and says, 'You're sitting on the pyro.'"

Though that evening may be memorable for the near catastrophe, Morello did have some highlights that will stick with him. He first appeared during the second song of the night, "Mr. Crowley," and also played on "Bark at the Moon," "Iron Man," "N.I.B.," and yes, finally "Paranoid" to conclude the night (according to Setlist.fm)

Tom Morello Reveals the Time He and Slash Almost Got Blown Up at an Ozzy Osbourne Concert (SiriusXM's Howard Stern Show)

50 Best Hard Rock + Metal Live Acts

More From Loudwire