Because you use the word "retard" out of correct context. And because you assume that those around you think that it's a fine use of the word, and that perhaps you're even a little humorous for using it. Your blatant use of this word out of correct context makes me feel a little sorry for you. I think, "Oh that's too bad." It makes me think that you're sheltered and uneducated and lacking humanity. That perhaps you've not grown since adolescence. It's really quite disappointing.  And that is too bad. Those are a lot of heavy feelings that I myself, and perhaps others feel about you because you choose to describe people and things as "retarded" as a casual insult. I feel like you are growing in number. I hear incorrect use of this word more and more every day. I really don't understand this phenomenon in our culture.

You may defend your use of the word out of context. To you I suggest that you think back to your last use of the word. Then, imagine finding out that the person you were speaking to has a loved one, a family member who is indeed diagnosed with mental retardation. Or that an individual with a cognitive delay was standing nearby and overheard you. Would you still defend yourself? Could you?

Though the root word "retard" and its offspring words can be applied beyond their use to describe cognitive disabilities in a human, its most widespread definition over time was such.  For years, "mental retardation" was standard medical diagnostic jargon, while words like "retard" branched out into our slang.  So, when one refers to someone or something as "retarded" in a casual setting, it is most often interpreted as an insult.  Though medical terminology has changed, most people with disabilities have lived their lives being referred to as "retarded" by peers, doctors, family members and society at large so we are very much still in a time where this word can cause a negative effect on people and cultures.    

I also think that it is important to look within oneself and determine why you feel that it is okay to speak this way about your brothers and sisters at the expense of an uninvolved population of even more brothers and sisters. Perhaps you do not know anyone with a cognitive disability. Perhaps you do not value people with disabilities or people with differences from you. Perhaps you are threatened by your similarities. Perhaps you do not know that you are capable of possessing real love and respect for an individual with a disability.  These are all very unfortunate things.  

Bad habits are hard to break so I'm not without suggestions here. When the word begins to roll off your tongue, switch it up at the last moment. How about re...diculous? Or, make up a word like re...posterous. Or re...pendous.

I hope that you'll not consider this for my sake.  And I doubt most people affected by cognitive disabilities or who have loved ones with disabilities really care either way about your vocabulary.  I hope that you will consider this for yourself and for humanity.  It's really just a simple editing technique that can have great, positive effects on the energy around you.  Simple = Big and Good.  Sign us up, right?

Thanks for reading - I know this isn't a lovely topic or splendid experience to personalize to oneself.  It's not especially enjoyable to tackle, risking alienating friends and loved ones.  But I felt the need and here it is.  It's not okay and I can't go along with it being okay.  Thanks for your consideration.  Take it, leave it, if you will.