One who lacks the most important organ, a brain. One who believes that the Earth is Flat, and that space doesn't exist and is just a 'dome' around the Earth and everything is a lie told by the government.
Feathers – \feath•ers\ Noun: Slang for hubris, arrogant, vain, narcissistic, selfish, self-centered. Originated from the cliché “He’s like a peacock so in love with his own feathers he’d high five his own shadow”
The server referred to John as “Feathers” to her co-workers because Feathers was so self-centered he liked leaving an intentional mess and bossing people around at the restaurant which gave him a sense of narcissistic pleasure and inflated self-worth.