I, first, saw it from forum about ways to say goodbye, and I've found there're lots of phrases following 'Don't let the door hit...' :
hit you on the way out
hit your a**
hit your a** on the way out
hit you where the good lord split you
What are the uses of 'don't let the door hit...' for?
and will it be different when changing the following phrase?
I would appreciate all your help.
It simply means to leave quickly.
If you go out the door slowly, the door would hit you.
So it means go fast or leave now.
Get the hell out!
It is an insult. It says "Get out of here FAST, go away - and don't let the door hit you on the way out."
Do not ever say this to a friend.