The word ‘derp’…where did it come from? I looked and the Internet told me (thank you Internet) that it came from South Park, but as far as I can tell it’s considered a very ableist word? I don’t use it, I don’t like it, but I did wonder where it originated.
The word ‘dumb’…When I was little, my mum told me not to use that word as an insult, but being little I ignored her, and I didn’t realise til I was an adult that it was offensive. I’ve stopped using it now, but do other people see it as offensive? Because I’ve seen people who are otherwise anti-discrimination use it, and although I’ve never seen anyone defend their use of it exactly I wouldn’t be surprised if everyone just figured it was too late to stop it being used offensively, like when ‘spastic’ was stolen as a word and The Spastics Society had to change its name. (See here.)
The word ‘retard’…I’m going to point you to The R Word.