Jesse and Miley have been in frequent contact since McCartney made a guest appearance on Hannah Montana two years ago. They're "on the phone to each other all the time, and they text each other," according to a McCartney pal.

Papa Cyrus will have none of it. "There's been serious flirting, but Billy Ray won’t let them date," says a Cyrus family insider. "It's driving Miley and Jesse crazy!"

Billy Ray's primary objection—beyond the age gap—is that Jesse has made the dating rounds in Hollywood, bedding such sophisticated dames as Hilary Duff and Aubrey O'Day.

Not helping matters is McCartney's steamy video for the song "Leavin'," which depicts a roll in the sheets between Jesse and a female model. (See the video below for proof of his lecherous nature.)

Good call there, Billy Ray. Wouldn't want your daughter's virginal reputation to be sullied at such an early age. That would be really bad.