Why do people jokeling insult each other?

Sometimes funny insults are a way to show love cause you wouldn't say those things to someone you don't love but there's definitely a line and a way to go about it. If it feels abusive and not funny then your either over sensitive or they are disguising abuse as a joke

Children's teasing of each other can be cruel if the person gets picked on for something the others think funny or unusual, but in general adults are mature enough to receive and give it without taking anything personally. It's known as banter. You've noticed it's not just your foster dad that goes along with it - your friend and her boyfriend are comfortable with it. It's all part of a healthy relationship. However, it depends on WHAT is said when you're with other people. If you know the other person is sensitive to something (like being overweight), it's unkind to joke about it in public. When I'm just with my wife I'll say things like, 'Sit down on a couple of chairs', and she'd probably clobber me and make some retort, but I'd never say that when other people are there.

BTW, high heels hurt only if you get ones that don't fit properly or have no padding inside. I wear 4-4.5 inch heels most of the time and walk miles in them, but very rarely do I get blisters or sore toes. I've worn them for up to 18 hours at a time, travelled on the train and stood for ages when there are no seats, walked on all sorts of terrain, etc. In fact, if I'd been in flat shoes my back would have been crippling me within a couple of minutes of standing or walking.

It’s called sarcasm. People who aren’t sarcastic don’t understand sarcasm. That is how they tease each other. They get each other.
I call my husband weird when he eats pizza with a knife and fork. His comeback is,”Sure if normal is weird.”
Lol

It's fun to insult one another, because it makes us laugh. I do it with my sister all the time.