Too many people talking at once in a room; certain friends not texting me back/not returning the same consideration I give them; when people have the TV waay too loud; racist/homophobic/transphobic/generally prejudice/ignorant people who can't be reasoned with; people staring right at my face the whole time they're talking to me; people who drive like assholes, e.g. honk 1 second after the light turns green; people who invalidate mental illness.

Although some of these aren't technically "over"reacting, but still. :P