Definition
The acute onset of paranoia in otherwise normal and balanced people triggered by the mention of a specific topic.
Origins
Coined in 2003 by Charles Krauthammer as Bush Derangement Syndrome (BDS) in The Washington Post article "The Delusional Dean".
How People Actually Use It
The condition of feeling an emotion usually hate or anger so intense or irrational, at a specific person, group, or ideology, that a response is triggered which is equally intense and usually irrational.
"Person 1: That dude is yelling about how x is evil incarnate. What's up with him? Person 2: Must have x Derangement Syndrome/Must be deranged/Must have derangement syndrome."
Source: Urban Dictionary