JOHN MAYER may have experienced SEXUAL NAPALM when he was with JESSICA

SIMPSON . . . but it sounds like things are going just fine with KATY PERRY, TOO.

The not-always-reliable "Star" says their grinding sessions are so intense, they're bothering

the neighbours. That's hot.

A source says neighbours have been complaining because John and Katy, quote, "have very

loud sex, keep very late hours and like to turn up the tunes."

Again....that's hot.