Is it haraam to call each other insulting names even as a joke say like between friends?
The Quran forbids using insulting names:
Nor shall you slander one another, nor shall you insult one another with names. (From verse 49:11)
The above appears to refer to instances of using insulting names with the aim of hurting others. But even if it is done jokingly, the above verse may still apply to it because the way it is worded keeps things vague. For this reason it is best to avoid using insulting names even if it is not done with malicious intent.