Means you have to be precise - not make a mistake or be off target.

"Dead on" means "exactly right", or "exactly on target", as in, "You got my meaning dead on." You could use "dead right" as a confrontational response: "You aren't saying that I have an annoying voice?" "Dead right I am." "Right on" also means "exactly on". It also can be used as a response, but it shows strong agreement: "Let's go have some fun today!" "Right on!" "Dead to rights" means "guilt can be strongly shown". An ensuing court case would be likely be "open and shut". "Dead serious" means "completely serious".