Not quite classical music, but Lester Bowie's Brass Fantasy offers slightly tongue-in-cheek renditions of pop tunes, and often rap songs.
Dig
Notorious Thugs from
The Odyssey of Funk & Popular Music (dig also the smooth version of the Spice Girls'
When Two Become One...it's not a rap song, but spectacular nonetheless.)
Also, from
When the Spirit Returns is
Player Hater...
Probably not what you were expecting, and I really doubt any 'serious' classical composers would have the creativity nor the
balls to try a stunt like arranging a rap song... ...BUT, maybe there's some out there. I dunno.