Back in December, Axl Rose made a surprise cameo appearance on Boomerang's New Looney Tunes, where he saved the Earth from an asteroid by singing a song called "Rock the Rock.' The writers of that episode, Rob Janas and Kevin Fleming, have finally revealed  how it all came together.

They were interviewed for the Guns N' Roses-themed Appetite for Distortion podcast, where host Brando got the inside information. As Fleming revealed at about the 36-minute mark, he got the idea after catching a show on Guns N' Roses' Not in This Lifetime tour and noticing that the band walked onstage to the classic Looney Tunes theme. After attending a second show on the same tour, while fantasy booking ideas for who they wanted as guest stars, Rose popped into their heads.

"The next part was trying to figure out an idea for him," Janas said, naming Snoop Dogg and "Weird Al" Yankovic as other celebrities who appeared on the show. "We had a whiteboard in our office and we would always scribble up different ideas on the board, and I think one that had been living up there for a while that we hadn't written -- we just hadn't figured it out -- was the Looney Tunes gang has to destroy an asteroid."

As part of the brainstorming process, Janas continued, they hit upon the notion of Rose rocking "so hard that he literally saves the world." Fleming mockingly added, "The only thing more powerful than a laser beam is rock and roll!"

Watch Axl Rose Perform "Rock the Rock"

Fleming added that Rose's reclusive public persona made them skeptical that their plan would come to fruition. It took "pretty tenacious" work by a producer to reel in the singer, largely because Guns N' Roses' highly successful reunion tour kept adding dates, which pushed back their planned recording dates. It got to the point where the writers considered scrapping Rose and going with Aerosmith's Steven Tyler instead.

Meanwhile, Rose's team were hands on throughout, asking to see in advance how the singer was going to be drawn. They came back with very specific tweaks, such as which bandanas to use and where the dog collars he wears should be placed, that they wanted incorporated into his design. These discussions continued in baby steps, with the show's creators remaining unsure that the appearance would happen until Rose actually set foot in the studio.

Rose's reputation as one of the definitive bad boys of '80s rock ("That's why he's the only one who can stop an asteroid," Janas said, "Because he's that powerful.") also meant that Janas and Fleming didn't know what to expect. But, he added, Axl "couldn't have been nicer," coming into the studio wearing a Wile E. Coyote t-shirt and introducing himself to everybody.

They were also originally scared to give Rose direction for fear of how he would react, even giving him leeway to change a line about the days when he wore a mesh jersey and kilt onstage. "But he was able to laugh at himself and that was the coolest thing about it," Fleming added. "and that's why you think, 'No wonder this dude is so successful and so cool.'"

After Rose recorded his dialogue, it was time to record "Rock the Rock," which Janas wrote, and it was then that they noticed a change in the singer. Where previously Rose had been deferential to the staff to get the right feel for the lines, the song was his territory. Janas said that Rose could tell from the arrangement that they were looking for an AC/DC vibe, and he did one take in his high register. After playback, he said he had an idea to record additional parts in his low and mid-ranges.

"Everybody in the room is kind of just letting him run the show," Janas said. "and can't believe it's happening and is just not saying a word."

The whole session took about two or three hours, and would have taken even less time if Rose hadn't gotten hungry. Late in the session, he suddenly got in the mood for a taco. "So one of his people went off and they got tacos," Janas recalled, "and he came back and he was like, 'OK, I'm gonna have a taco, and then I'll come back and I'll finish up." The crew expected a 10-minute break, but Rose went into the hallway, took a few bites and walked back into the booth.

"He stands there with his headphones on," Janas laughed. "[He's] not saying anything, but, like, he's ready. OK, he's done. The break's over. ... Get out of the bathroom. He took, literally, like a 30-second break and then he started singing again."


Every Guns N' Roses Lineup Change (We Think)

More From Ultimate Classic Rock