For fans who need further confirmation that John Mayer is a jerk, take a look at Exhibit A.

Rocker John Mayer, 31, stands accused of faking out his fans. Hollywood insiders claim the future Mr. Aniston has a habit of teasing his adoring fans with phony autographs signed “Engelbert Humperdinck” instead of “John Mayer.”

“John signed one of my autographs with the name Engelbert Humperdinck,” disgusted Mayer admirer Robert Isherwood tells Life & Style.

Humperdinck was a popular British pop star in the ’60s.

“I crumpled it up and threw it on the ground,” Robert continued. “Why would I save that?”