By marking out an insurmountable division between acceptable and unacceptable individuals, you can create the cozily claustrophobic sensation of being “we few, we lucky few” against the marauding inhuman hordes outside your social network—a feeling mimicked by films about the housebound survivors of zombie plagues.
I tried to do exactly this while in high school. Luckily, my friends were too clever to join me in this venture.

