WTF should be an emotion. There isn't yet a single word for the sense of seeing something that totally boggles the mind; it's related to confusion, but not the same thing. Confusion is aversive, while WTF leads to LOLs and a state of blissful unawareness of what's going on. It's more like confusion feeding into a jolt of happy surprise.
The Dadaists and surrealists didn't quite have a name for it either, but they certainly understood WTF. While they wrapped their work up in a philosophical movement and reaction to existing art, it would never have caught on if people didn't have an inborn love for the non-sequitur.
Many artists get their inspiration from dreams, and dreams illustrate that we all have nightly encounters with WTF. When left to their own devices, our brains rejoice in the random. We're built to like it, and I suspect this serves an evolutionary purpose. Love for the outlandishly mysterious is part of the same drive that allowed early humans to figure out why the clashing rocks and the sparks and the fire always went together. It's the same stuff that fuels science today.
We must celebrate the random. Bathe ourselves in nonsense. WTF.
Some more pictures from the internet's leading source of WTF, Picture is Unrelated:
Edit June 3: See also Calvin's flattering post that expands upon the notion of WTF.