Following a year in which numerous DJs mixed Jay-Z's vocals with the music of the Beatles, Metallica, Weezer and others, the Brooklyn, New York, rapper tipped his hat back to rock fans by performing at two unlikely concerts over the weekend.

The stranger of the two was Friday night during a set by the jam band Phish in Coney Island in Brooklyn, at the group's supposedly final New York-area show (see "Phish Bid New York Fond Adieu At Farewell Shows"). After the veteran rockers played "Wilson," the second song of their second set, Jay hopped onstage and the group backed him on "99 Problems" and "Big Pimpin'."

The rapper made his second unannounced showing the following evening at K-Rock's eighth annual Dysfunctional Family Picnic radio festival in Wantagh, New York, which featured the Strokes, the Darkness, Cypress Hill, Brand New, the Yeah Yeah Yeahs and others. The Beastie Boys had just finished their set, and fans were on their way out of the venue when a voice blared over the PA warning them not to leave, because something special was coming up that would "blow [their] f---ing minds."

Then Jay, dressed in baggy light blue jeans, a purple-and-white shirt and shades, blasted through "99 Problems" for the thousands of rock fans in attendance.