I'm really pleased to see people thinking about ableism and ableist language. It's so easy to just say what you've always said without thought and I appreciate anyone who stops to think about it.
"Duh" is the word I'm personally trying to remove from my vocabulary. As I have ADHD and am forever losing or misplacing things, it pops out of my mouth automatically far too often. I only began thinking about it recently, and as I have a couple of neurology-based disabilities it really is not ideal for me to say something that's insulting to people who are like me- by saying it, I'm putting myself down (internalised ableism) too!
"Lame" is tough because it replaces a whole lot of words. I do understand how difficult it is to replace it. I liked the suggestion of "bogus" (but didn't want to hijack that person's comment).