This riddle asks: what gets fuller the more you take out?
A playful answer is empty space.
As you remove more objects from a drawer, room, box, or container, there is more empty space inside it. In that sense, the space becomes “fuller” of emptiness the more things you take away.
The wording is designed to sound contradictory because we usually think removing things should make something less full. The trick is to change what you are measuring. You are not filling the container with objects; you are increasing the amount of empty space.
That reversal is what gives the riddle its punch: taking things out can make the empty space inside grow.
