Frighten/scare the life out of somebody
Definition 1 of 1
Pro Tip 1/3Intensity
Used for situations of extreme fear, not just mild surprise. 
The horror movie scared the life out of me.
Pro Tip 2/3Figurative
It's an expression, meaning no one actually loses their life from fear. 
You jumping out at me scared the life out of me!
Pro Tip 3/3Informal
Common in casual speech but not suitable for formal situations. 
She scared the life out of me, sneaking up like that!