The part after sex where the man demands his woman to go and make him a snack, the refusal of which results in the the man throwing her down the stairs and pooping into her mouth.
Luther asked Ethel to make him a sandwich after having sex with her. When she ignored him he gave her a late night snack and she woke up at the bottom of the stairs with bad breath.
Opposed to midnight snacks, late-night snacks are the snacks one eats after getting home from partying all night.
"dude I'm so f**** wasted right now, but also so damn hungry, I just wanna get home and eat that late-night snack!"