dissentomatic 

A term used to describe somebody who automatically will disagree with everything, because they refuse to appreciate

People who behave like this will try as hard as they can to figure out how something can possibly be incorrect or false regardless of reason, practicality, or anything else.

Not to be confused with hater

Sam: It's cold outside

Dissentomatic person: Actually, the current temperature is -40. It gets much colder in Antarctica, so by comparison it is actually chilly. You are wrong Sam, haha!

Sam: (pulls out pistol)

dissentomatic by Optical_Epilepsy December 11, 2011