What's the secret to [artist id="1962774"]Katy Perry[/artist]'s rather meteoric rise to fame? Apparently, it's Coca-Cola and Tylenol.

At least that's what we learned backstage at London's O2 Empire club, where she just completed a sold-out, two-night run. The scene in the dressing rooms was hectic -- plenty of last-minute costume changes and makeup sessions -- but Perry made it a point to complete one preshow ritual that she credits for putting her over the top.

"Every night, an hour before my show, I have some Coca-Cola and a Tylenol. And I don't know if it's good or bad, but I think it just messes with my mind, to let me know we're going to have a great show," she said. "It's probably not the greatest idea, since caffeine isn't usually good for singers. I'm probably freaking out so many vocalists who are watching this right now. They're like, 'That is a horrible idea!' Well Roy Orbison did it, and he's a classic."

We have no way of verifying that, so we'll just take your word for it, KP. Other highlights from our backstage jaunt: Katy and her backing band -- who are all decked out in matching pink tuxedos, which apparently explains why they're called "The Pink Flamingos" -- doing a preshow tribute to director John Waters (you know, since he directed the cult classic "Pink Flamingos" and all) and Perry sneaking on to the stage to wave hello to her fanatic fans.

Oh, and we also learned that there's a far less scientific (or musicological) explanation for the whole "Coke and Tylenol" thing:

"My mother never let me drink Coca-Cola," Perry explained. "That's really why I think I do it."