I found a youtube video explaining that giraffes have four stomachs. They vomit from the forth to the second or first, and very rarely does it come up. https://youtu.be/7EXnc8SXWV8?t=70
That's an impressive superpower.
Looking harmless and then suddenly violently puke like a fire hose stream on some poor bankrobbers or something.
I bet that it wouldn't need to be some strong acid to be an effective repellent.