It means coming back to life as a RETARD, not as a hillbilly.
The person who posted the previous definition was thinking of reintarnation
Damn, it was quite sad that Mark's ubergenious rocket-scientist son had just died in an explosion while working on the latest space shuttle 9 months ago. However, my neighbors next door just had a kid that looks like Mark's son when he was baby, though I heard the kid was diagnosed with Fragile X
syndrome! It looks like Mark's son has reintardated(reintardation)! Whoop-dee-doo.
Mark H. Proud Urban Dictionary Slang Author since February 2004.