Gym rats use these phrase after a hard workout to state that they are ready to battle their demons once again.
That is because 3 am is also called "the devils hour".
A statement-warning given to someone that what they are about to do may backfire and they may end up regretting it. Another spin on "if you can't do the time, don't do the crime.".
Why did you tell Jennifer you saw me downtown last night? If you are gonna stir the pot of shit be prepared to lick the spoon. After all, your closet isn't so tidy.