A way cooler way of saying stfu/shut the fuck up. It is just a way of sounding you the abbreviation. Only the coolest people can use this word. And it works perfectly in any arguments
Annoying hoe: Oh my god dude your pants just aren’t passing the vibe check Guy: Bruh steefoo nobody gives a shit about you or your family
Cool Person 1: "Oh my god, have you seen Christina? She's wearing the exact same dress that I wore yesterday!"
Cool Person 2: "Don't worry about her. Everyone knows she's a stepfoot."