The word Retard is used derogerotarily as an insult because if refers to people who are, in a sense, not as good as a 'normal' person... (not being mean, just trying to make it so this girl can understand this).
It is an insult that refers to the very people that are in teh special olympics.  it does not mean anything else.
The fact that you can call someone a retard as an insult, yet still feel good about yourself because you volenteer at the special olympics makes me fucking sick to my stomach.  I have a couple peole I grew up with who were in the special olympics as athletes, and I'd really like to have you call someone a retard in front of them.  maybe then you could see the sadness and anger that they feel when that word is used as an insult.
As for you comparing this to the word 'gay' I'm glad you did, because the same exact thing goes for this word, and it's easy for me to kill 2 birds with one stone here.
Calling someone gay is insulting because you are refering to them as a homosexual.  That is why it is an 'insult'. (I personally don't feel the word gay is an insult and I ahve friends who are homosexuals and I most definitly do not consider them lesser people).  Again, I would love to have you insult someone by calling them gay in front of these friends...They could do a far better job of kicking the shit out of you than I could.