Perry made the revelation during an interview with The Chicago Sun-Times. He said, "I did a [recording] session with Paul McCartney a month and a half ago for a private thing," Perry told the paper earlier this week. "I met him once or twice [over the years] to say hello.

"To spend 6 or 8 hours in studio with him recording! He makes you feel like [you're recording with just another guy]. He just happens to be a mother--g huge talent! Everyone's in the room at once; you play until you get a good take."

When asked what it was like to play with McCartney, Perry said, " It's the great ego leveler. I was in the studio with Alice Cooper and Johnny Depp, playing guitar, and the three of us are looking at each other like, hey, we're sitting here with Paul McCartney! And we're all looking at each other like open-mouthed kids. Paul was really nice. He's all about business [when he's recording]. At 72 he can still hit all those notes."

Perry wasn't ready to offer up details about why they were all in the studio together. He said, "It's a project that were keeping under wraps for now. There will be [an announcement when the time is right]."