let daylight through
euphemism To shoot or stab someone. The image is that of a wound in one's body through which light could shine. He said he'd let daylight through me if I didn't hand over the briefcase.
let daylight through
Shoot or stab a person, especially fatally. For example, Stick up your hands or I'll let daylight through you. This idiom alludes to making a hole in someone's body. [Slang; early 1700s]