That they are cracking jokes about you

To be "on (someone's) head" is to make fun of someone or "roast " them. My little brother insists this is already a phrase so it ought to be on here

when someone wants to fight or kill you

When someone passes some kind of alcohol or drug up, and gives it to you.

having more difficulties than you can manage

a phrase used by every white Australian male PE teacher when you fuck around.
you're better off to stop being fucking annoying or they'll call you fuckwit for the rest of the year.

This is when something annoys to the point that you feel like your head is going to explode i.e. complete frustration