Hi there! I dont have any advice, but I do have some insight that might make you feel a little better. I have read that babies do this to test how far down it is by watching the object fall. Because they are unable to test it out in other ways, this what they have come up with
It also helps them learn about cause and effect. It's like, "Well if I drop this on the floor it makes this sound and bounces. How fascinating! Oh, and mom gives me this reaction which also very interesting. What a fun game!"
Anyway, when this little game is on your last nerve just remember your lo is learning so much from something so trivial.