Reacting angrily can take many forms. Roaring, snarling, bristling and flying off the handle are all ways to express anger. Roaring is a loud, deep sound made by an animal or person to express anger or aggression. Snarling is a low, threatening growl, often accompanied by bared teeth. Bristling is when the hairs on the back of one's neck stand up in response to fear or anger. Finally, flying off the handle is an expression used to describe someone who suddenly becomes very angry and out of control.