scare the shit out of somebody
scare the shit out of (one)
vulgar slang To shock or frighten one very suddenly and/or severely. (Hyperbolically alludes to frightening someone so badly as to cause them to lose control of their bowels.) Don't sneak up on me like that, you scared the shit out of me! That car accident seems to have scared the shit out of Janet—she's still shaken by it.