Having a short fuse is an expression used to describe someone who has a tendency to become angry quickly. It is often used to describe someone who is HOTHEADED, or easily provoked to anger. This phrase is derived from the idea of a fuse on a bomb, which is a short length of wire that will burn quickly and cause an explosion if it is lit. In this context, having a short fuse implies that the person's temper is likely to explode quickly.