Katy Perry isn't just on tour -- she's on fire!

So it's no wonder that the pop star, 26, needed a cool down during a super-sexy cover shoot for Rolling Stone. Wearing a skimpy yellow bikini and see-through rain jacket that shows off her incredibly fit, curvy bod, the "Last Friday Night" singer literally got hosed down.

Russell Brand's wife stayed dry but got even edgier in other segments of the Miami shoot, as orchestrated by controversial, acclaimed photographer Terry Richardson: Strutting in a skin-tight pink mesh on a roof top, playing a kinky pin-up girl in a dress that looks just like a Hershey's Kisses wrapper (white paper tags strategically placed!) and more.

Watch the steamy behind-the-scenes video now.