Ok, so I had to look this up, I didn't make it up, it's from the Urban Dictionary. Read the last line of the definition #2!
1. donk
a very round, attractive ghetto syle booty
derivation: shortened form or badonkadonk
damn, i wanna hit that fine donk.
buy donk mugs & shirts
2. donk
Any POS late 80's or early 90's American heap (preferably an Impala) that has large enough wheels installed until it resembles (and rides and handles like) a Conestoga wagon. This is done so it sits up high enough so as to be at the same eye level as the Playas with real juice ridin in their Escalades. Adding in a bad candy paint job and Wal-Mart sub box completes the transformation.
With no money left over for necessary suspension and brake upgrades, the lifespan is limited to a few drug runs or the first Police chase, whichever occurs first. That donk is fly and ridin high.