Answer this riddle if you can

A friggin' lunatic.

it could be a vector path (aka a drawing)

It is a hole

Hi madman,

That went straight past me. A hole in what?

yeah...i don't see how a hole works either. i guess you are assuming it is a cylindrical hole through a box, so that when viewed from one dimension it is a square, and from another dimension a circle? I was thinking of this originally...but this would still have sides, even if (technical term coming up) the normals are flipped.

I am still happy with my drawing answer...you can draw a circle, you can draw a line, you can draw depth perception, it is more than just a line (it is an abstraction of a visual scene), and your drawing has no sides (only the paper does).