Uh, ok? It's bigoted language, it's outdated and no longer used in the medical fields. Intellectually disabled is the accepted, appropriate term. This isn't my opinion or idea, it's the standard now as determined by both professionals, and those who would have formerly been labeled as that word.

Similar to saying someone is "spazzing out" or is a "skitzo". Or saying some inconvenience is "gay". It's not appropriate.

You do you, but it's a slur now. you can SELF DESCRIBE as whatever you like and use whatever labels or descriptors for yourself you see fit. No one can police that. But it is bigoted speech to use slurs about things like disabilities, orientations or similar for other people.

To help you relate: it would not be appropriate to "make fun of" someone by saying they have autism or ADHD