“That is retarded!”
The word ‘retarded’ started out with a specific meaning. It defined people with mental handicaps. Over time, people have used it to degrade others. We use it as slang. “oh, man, you are retarded!” With each use it transforms the meaning. Now, people that are technically retarded are valued as “less” of a person, than one who is not.
So, thoughtful people created words like “mental handicapped”. This was an effort to put retarded people back in a place of equality.
“Sticks and stones may break my bones, but words will never hurt me.”