Being the pun of o joke and how we talk to each other
When people use insecuritys about birthdays against people as a joke about them becoming old, without knowing why this freaks them out, you're being rude and not a very good friend.
When you joke about people not leaving they're apartment. Joke about them sleeping so much, meaning that they're lazy, you're being rude. How can you not see that it's symptoms of depression you're laughing about?
When you're saying that "all you're chlothes are like tents on me" especially when you know this person is struggling with eating disorders, or even if you don't know, I'm sorry you're still a bad friend.
This just shows how much you ignore you're friends and people around you, how you don't listen or even know the people around you.
When you refuse to think before you speek you're being a bad friend cuz you don't care, you're just looking after yourself. When you don't listen to the people around you, you're being a bad friend cuz you should care about what they say, how they feel.
Stop being a bitch, stop joking about things that really hurt people.
I have a harsh humor but I don't joke about you're eating disorder, I don't joke about you're struggels. It's an easy way to do a joke and it just shows how bad you are at joking, and being a friend. 

It's not just jokes either, it's about how we talk to each other, or how we say things.
It's about how u comunicate and how u lack in it. Think, before, talking. It's not that hard. If you find it hard it's because you're egoistic and don't want to be better for others, it's because you're egoistic and don't want to be responsible for you're own words.
You can't just say you're a feminist, anti racist, HBTQ allied and shit out words that is hurting, that is damaging. And when you're being called out stop feel sorry about yourself and listen.