How do I get nero-typicals to not say "ret*d"?
You said you were not ret*d, but your mother said you were because you have aspergers. Not only is your mother wrong on medical grounds, but your mother called you ret*d. That sounds vindictive, in fact callous for a real mother to say.
Low functioning people when able to communicate are shown to have an IQ often above the very low threshold below which children are called ret*d. Equating autism and mental retardation belongs to the 50s, nothing more than quack science by today's standards. It's the sort of incompetent thinking that would have held back Temple Grandin.
I never said my mother told me I was ret*d. Other kids did.
There isn't really a pleasant way to go about it.
NT's will often mock things society has once had a problem with or still does.
They may even refer to using a person's name in a degrading manner such as "Oh that's so Chris!" to describe someone doing something peculiar.
You could however experiment. Most of the words did not start off with a negative implication. They ended up that way over wrong usage in an insulting manner. You could do it right back.
With any interests someone who is NT that keeps calling everything gay or ret*d you could say anytime they do something off or silly "That's so (insert person's name)" For example if the person's name is John. You say "That's so John!"
Eventually their own name will feel like a negative word. Once the person demands you stop saying that then you in return demand that the person stops saying "ret*d" or "gay". Otherwise you'll just keep going.