Parents' Nightmare (Age: 20)

If Miley Cyrus baring her shoulders was deemed scandalous by the parents of her tween-age fan base, what kind of effect will her running around with a 20-year-old underwear model have? One parent doesn't seem troubled—the Disney star's manager dad, Billy Ray, who may have brokered the relationship. Now that Justin Gaston has landed the world's most worshipped tween idol, he's redefining what boyfriend means to girls ages 4 to 14. Out: dimpled, asexual Zac and Cody. In: strapping dude who earns a living showing off his package. When teen-pregnancy rates climb, guess who will get the blame? Of course, Gaston made sure to take Cyrus to a church service in Pasadena on one of their first dates, and the starlet maintains that there'll be no sex until marriage. Even if that turns out to be true, in many parents' minds he's already finger-banging their young daughters.