Well the dictionary definition of "Retard"
verb (used with object)
1. to make slow; delay the development or progress of (an action, process, etc.); hinder or impede.
So who's "retarded" now?
I always remember this from an episode of CSI: Crime Scene Investigation (called Snuff) where a young man with Down syndrome was murdered and this guy kept calling him a retard and Grissom responded with this quote once they found the man responsible
Grissom (to murderer): The definition of the word 'retard' is to hinder or hold back. I'm afraid your life is about to become 'retarded.'
Love it!