Here's something you've probably never thought much about: Is there a way to get a round disk through a smaller square hole in a piece of paper?
It seems silly, right? Of course not, you say! It's impossible!
Well, not always, according to this video by Numberphile featuring a mathematician from Stanford University, Tadashi Tokieda. If you fold it up just the right way, the round object will go through easily.
According to Tokieda, "It has to do with the intrinsic, or inner dimensions of the sheet of paper, which is two dimensions, and the fact that the sheet evolves and flourishes in the three dimensional space."
Still confused? We don't blame you.
Basically, by messing with the paper (but not breaking it), you can create a straight line out of two of the four sides of the square.