What does ' waiting for the other shoe to fall' mean? Where does the image come from ? Is it an old saying?

It's from an old joke, I guess set in a boarding house, about a man who wakes his downstairs neighbour every night by throwing his shoes on the floor, before getting into bed. They argue about it, but the man usually forgets. One night he drops one shoe on the floor, then remembers his neighbour, and lays the other one down gently. He thinks he's done a good deed, but the next morning his downstairs neighbur is more furious than ever before, having lain awake all night waiting for the other shoe to fall.

If I had to guess, my upstairs neighbors drop bowling balls. Maybe I will post the "other shoe" story on our condo website... I doubt they'd get the hint though.

What makes someone take off their shoes and drop them on the floor? It seems much easier to me to take them off at floor level and never pick them up at all. Perhaps it has to do with the excessive weight that the folks upstairs carry?

Oh now I'm just being mean. I really didn't know the story of this saying though.

I've most often heard it phrased as "...drop" rather than "...fall" but never knew the origin. Thanks, n³, for the explanation.