Would depend per person and the timing. For women, it can be weight. For men, it can be their manhood. All depends..heh.
The "worst" insult would depend on the person and what they're sensitive too. For instance, a person who has a perfect physique or even average physique probably wouldn't be too offended by being called fat unless they have crazy self-esteem issues. It's kinda funny how people usually only insult people to take the attention off of their own imperfections or they're just a complete a-hole, but usually it's the first.
Hm, I don't think insults are cruel, it's what you make of them. You can let people who really at the end don't matter hurt your feelings? lol. Take it as a compliment they taking the time to put attention on you. I just don't stress over little things.
I can't think of anything right now but I think lieing, cheating, making fun of someone's belief or feeling.... maybe.
does it have to be verbal? If not i think ass fxxk a guy's mother and put it on the net will be the worst...
Probably insults that have to do with wishing a disease or illness to someone. I never use them, I don't think anybody should.
i've been insulted many times but the worst i got is making me a very small person... but i will get over it. one of life's lessons.