as an example if a trans woman wants to call herself a tranny or inset other slur here shes allowed to use those terms for herself if her trans friend has similarly given her permission to use those words her friend can call her one and she can call that friend the same it doesnt make it ok for cis people to use those terms for trans women though nor does it mean the same thing when a cis person does its just not the same thing just like its not the same thing if a gay guy calls himself a fag vs if straight people call gay men fags and so on