let that sink in

buy to let

To purchase a property as in investment, and to let it out for rental instead of living in it

don't let the door hit you on the way out

Used as a command to leave in haste, or to indicate that one is glad, or at least unmoved, to see the addressed person leaving.

everything and the kitchen sink

Alternative form of everything but the kitchen sink.

everything but the kitchen sink

Almost everything, whether needed or not.

let a sleeping dog lie

Alternative form of let sleeping dogs lie.

let bygones be bygones

To disregard or ignore a past difficulty in a relationship or an offence (when dealing with another individual).

let crazy stick its dick in you

To have sex with a male deemed insane.

let down

To disappoint; to betray or fail somebody.