What if I am very secure about given topic (e.g., balding), so I feel very comfortable joking about it, even "at my cost". Should I disregard the fact other people might be insecure about it, because I don't mind people "doing unto me" such jokes?
"Do unto others..." isn't a compressed file that expands into generic rules for every situation. (If life was simple enough to be covered by a set of generic rules we wouldn't have evolved these huge calorie-guzzling brains on the ends of our spines, eh?)
You might think the situation is too broad or complex etc, but your calorie-guzzling brain can work the many and various context-dependent scenarios out. For every wrong there is a right answer. We live in a moral world.
Luckily, its not your job to sort the world out. You can only work on yourself and ensure your actions are aligned with morality.
PS I would reply sooner, but as I have received so many downvotes I get a message to slow down, that I am posting too fast.
What I am trying to say is that the golden rule and its applicability is far from obvious. You can consider interpreting it correctly the most basic "advanced morality" you asked about.
> Should I disregard the fact other people might be insecure about it, because I don't mind people "doing unto me" such jokes?
You seemed to show awareness that people might be insecure - so you have the information you need to exercise your judgement in this case. And every case will be resolvable if you want, via the application of reason. But this is a free will universe - you can ignore the information that you have, but then, you also know what that means.
If you want to say whatever-it-is isn't obvious, that's fine. You don't have to follow what I say. In truth, what I (or the golden rule say) isn't important - words are pliable if you want them to be and work at it. You already know what is right and wrong, what intent your actions have behind them - the words are merely decorative; an attempt to communicate.
My view is that we judge ourselves. If you think you can kid yourself and via word games so you can have you cake and eat it, go ahead - but you have been told. There is a difference between nascence and ignorance - ignorance is a choice. All the best.