Race. The social constructing of it, the history, the madness. I teach that race based discrimination is a form of mental illness. I also believe being constantly"raced" can drive one into an anxiety /neurosis. I also think accepting the constructing leads to psychosis. For instance the Purple Folk enslave the BooBoos and tell them you are now the Pink Folk. The Pinks then assert after their freedom a few hundred years later that pink is beautiful, that they are inherently pink without regard to the thought that "pink" is a labeling given to them by the Purples so you're still acting out a level of brainwashing by even defining yourself as Pink, even if you're in "opposition" to Purple hegemony.
See how it is insane from all facets? The pink purple challenge makes it difficult to even discourse with other people of color because they're defining themselves within the matrix even as they seek freedom from it.
This paradigm is why racism still grasps society, because no one will drop their race rope. Imagine if tomorrow 100 million people stopped checking off anything but other or mixed on race based questions? Then what would happen? We'd identify by ethnicity, culture, land origin but those things aren't consistently irrationally divisive so you would become forced to human to human interaction.