Cornflake

An unthinking or insane right-winger -- in other words, most modern right-wingers.

Cornflake can also be used as an adjective, e.g. a cornflake Trump supporter.

The term is a variation on the pejorative "snowflake". The "corn" suffix references the fact that conservatives and right-wingers typically come from red states that grow corn.

The right-wing propaganda site Breitbart launched a campaign against Kellogg's in 2016 after the company pulled their ads from the site for political reasons. The word "cornflake" as a derogatory term was first used on the Breitbart forums in that context.

Worker #1 "Did you see those cornflakes whining about the MSM?"

Worker #2 "Yeah, that Kellyanne is nuts."