If you've ever played pictionary you'll see the level of abstraction we can manage is remarkable too.
It is unmistakable how much the difficulty level ramps up when you're paired with those of an unlike-nature to you. Sometimes that level of abstraction is taken way outside of generic context clues.
We use very generic "words" (eg egg, tree, bike, cloud, plate).
When you're using your foot to draw you really have to distill down to the essence of the item. Yes there is a deal of guessing but in some way the image (however unlike the object) has to have some element of the Platonic nature, if you will, of the object being drawn.
Fun!