Grandpa Joe: I haven't stood in 20 years.
-I personally don't think he literally lied in bed that long. He probably was just overexagerating in a sarcastic manner.
-Similar to when you don't see someone for like a year, you would say, "Wow! I haven't seen you in like a million years", even though it's not literal.
- he must've been bedridden for 1-2 years at the most, it's not realistic for a person to successfully stand, walk, and dance so quickly after NOT walking for a while.