But that's just it - how "obvious" something is is completely subjective. I was baffled that the other person took me seriously because it seemed obviously ridiculous to me. After a while I just accepted that I can't be sarcastic with people I don't know well enough if I care about getting my point across.

Point was that it's not necessarily "because you made me look stupid". If that was the case, I would believe to be utter moron by now. (Getting sarcasm is not my thing, but that doesn't keep me from using it..)