Privileged, trust funded white kids who subsribe to the hipster lifestyle (because they can) since they have no worries about money, a job etc. They can then devote their lives to drinking cheap beer, being ironic, and wearing too small clothes.
A prankster who throws a turd into a discussion. Superficially, they are just another participant. But in reality, they are less interested in persuading others than in making a splash.