You scared the living daylights out of me.

Have you ever used this term?
What even are daylights?
Daylights is an 18th century slang term for eyes.
In this context; To scare (or beat) the living (an intensifier that means "very" or "real) daylights means to dish out a merciless beating or frighten someone out of their wits.
I hope you or I never have to use this term literally.