In the context of a joke a lot can be got away with, but using something as part of everyday language imo is different.
Thats the thing, my limit for private jokes between friends is different to what I would be prepared to say on a public forum, where anyone could be listening. That includes parents of such children, who spend all day loving & caring for them. I dont think its fair, considering the priviliged position we are in, to start mocking such disabilities.
I have a sister with a mental disability, I have seen her teased by "normal" children. That still doesn't make the word, in the way it's used, the way I do, as offensive........unless it is said to her, to insult her for the way she is. The way she really is.
I would never insult someone with something that was real to them, that could cause them pain through my words.
So if someone is truly obese for instance, and we argued, I wouldn't call them fat, I would call them something else.
Sounds really oddly thought out when I say it, I know, but it makes sense in a way that fits well with me.....or used to.