- Leave a polite comment on your post explaining why you're unhappy with the edit
- Roll back the change from the revision screen, or manually restore the "style" back to your preference.
If they come back and edit it again, flag your own post for moderator attention (and explain what's going on) and if we agree with your argument, we'll have a chat with the editor and they'll stop editing the post.
I went fishing for some context and found the question this is probably about. There are a few things I would say about what has happened:
- Why are people editing closed questions?!
- Citing XKCD with an image is unnecessary. A link would have sufficed if you felt you really needed to reference it.
- There is also a copyright issue on the image. You do not have the right to grant Stack Exchange Inc a commercial, all-encompassing license to the image - which is what you do when you post.
- Changing "jerk up" for something that is more technically correct (ie "skip") is a good edit.
- Removing over-hyperbolic, over-emphasised colloquialisms like "really sucks" is also generally regarded as fixing formatting abuse.
There are things here that both you and the editor are doing wrong, chiefly worrying about a question that was closed three months ago. If I were the editor, I'd wonder whether what I was doing was really a good use of my time, and if I were you, I'd be questioning if it really matters at all.