I'm going to joke about my friend being poor
Is being poor a joke to you?
Nobody ever mention's it I think it will make him sad.
You think that it is just a joke, but to that friend it will crush him because he's poor and already dealing with a lot of negative things. Do you really want to put him through something like that?
I don't care if it makes him feel sorry for himself.
Not caring about your friend is going to hurt him even more, and how would you feel if a friend of yours hurt you and didn't care? It's better to show your friends compassion and stay away from them if you can't.