When Pranav drops something, I say "Uh oh.". He has been imitating me, but says "Uh aah". Sometimes he says it after dropping something. Sometimes he says it before, which is a useful thing, because I can rush to catch whatever it is that he's dropping.
To him, all it means is " on the floor". I discovered that only today. I was holding him, and he pointed to himself and then the floor, and said, "Uh aah.". He was asking me to set him down!