Uncomfortable images in art and nature. I advise caution with images at the end (they enforce more eye movement). Why anyone would care? It is quite good for computer vision to distinguish unsetling images.
I have probably accidentally created "homework" tag for two questions. One was self-deleted and the second got this tag stripped. Then I have read meta about avoiding meta-tags. Sorry for that. But the tag seems to be gone, right?
@Evil The homework tag has been blacklisted; it can not be used anymore. (I don't think you created it; it was probably one of the first tags created.)