Don't use/remember/understand the expression "sweat like a horse."
Don't realize that "reckon" is a real word.
Don't understand that "Might could do something" means something different than "I might be able to do something." Apparently, we got this construct from our Scots ancestry.
There are tons of others. These just came up recently and were on my mind.
“Windmills Do Not Work That Way!”*
The life and hobbies of a firmware/software developer.
- City Kids/Northerners