I had a concern about your use of the word "lame" as slang for "bad" or "un-cool." I imagine that it's probably something you hadn't really thought about, since that's true for most people. I wanted to let you know that it has a similar discriminatory sting to racial slurs, because it's been used in a similar way. It came from a simple description of a group of people who were considered lesser, and took on a negative connotation that eventually overwhelmed its original meaning in most people's minds (the word "gay" is like this too). But it still gets its "bad" connotation from the "less worth" status of those people, and thus reinforces the idea that that group IS lesser. If people always rolled their eyes and said your name in a disgusted tone when they didn't like something, you'd feel pretty sure that those people didn't respect you or perhaps actively hated you. If you do that with a word that describes a group of people, you're doing that to many people at once.
This builds on the the "it's not expressive or useful anyway, and it hurts me personally" post I wrote about two years ago.
ksej also points out the consummate laziness and lack of imagination in using ableist slang.
This isn't about offense. It's not about being polite. It's not about being "PC." It's not even about being kind. It's about living in a world that is structured to enforce inequality, and the fact that language is an extremely powerful tool for policing difference. It's about the fact that using words which have discriminatory connotations contributes to discrimination. Like with the word "gay" -- even if the people you know who fall under that umbrella don't have a problem with it, it is still used to reinforce the idea that being gay is bad. Even if it doesn't hurt the feelings of those you know, it still causes harm.
I'm not asking people to not use this word. I'm asking people to consider why they might let a habitually used word remain in their vocabulary upon learning that it has been -- and still is -- used to remind people with disabilities of their station, of their "inferiority," of their lack of belonging and acceptance.