This meme is a good example of something I've been considering. This post is very much talking about prison rape which is just as horrible as rape in any other situation. I wouldn't say this post does any harm itself, but it is rather a result of harm. There's nothing harmful about rape jokes themselves though. Merely the fact that rape exists so that we can make fun of it.
tl;dr Making fun of something isn't an endorsement, approval, or cause of that something. It is the result of that something existing.
tl;dr Making fun of something isn't an endorsement, approval, or cause of that something. It is the result of that something existing.