It is a tounge in cheeck-expression to describe the elitist attitude that not seldomly shows itself in the T-community, for instance when a Post-op goes; "Why would a T-woman want to keep her penis??", "Why would a T-man/a Cis-man want to have a Vagina?", "->-bleeped-<-s are just gay males", "Why would anyone want to be both genders?", "Why would anyone want to be neither gender?" and yada yada.
In short, usually, a term to describe the standpoint that Post-op transsexuals are the only "real" ones in the Community.