On the door 守门，看门
We should be able to get in free because I know the guy on the door.
John is a door-to-door salesman.
Show sb. the door
Thank you so much for coming in for the interview. John, would you please show Mr. Porter the door?
Sir, if you don't calm down, I'm afraid I'll have to show you the door.
keep the wolf from the door
This loan will keep the wolf from the door at least, but I'm worried it won't last long.