For intelligent people only. (Evil laughter in the background.)
If you want to know, this is a blowup image of the coffee mug I use in the office. I know, it’s not black. I wish it were. But when I saw it several years ago, I liked the joke so much that I made an exception to the “as much as possible black” rule and bought it. If you notice the signature, the original artwork is by Gary Larson, creator of The Far Side.