A user named "FeelingSick" posted an "answer" with some extremely unsuitable content at the question How do "proofs" work in mathematics, down to the basic level?. [Warning: the image might be disturbing to some people.]
It has 9 downvotes as I write; if I understand correctly it will be automatically deleted when it reaches 10, so I'm posting this to try to speed the process along. I also flagged for mod attention, but I think it's imperative that the answer be deleted ASAP. I've never before seen something like this on M.SE, and I hope not to again.
Needless to say, I also think the user should be banned permanently.
Update: OK, it's gone.