When you're sprung and in a club, wanting to bang somebody, but the only chick DTF is ugly with a butter face. You take a BUTTER SHOT or two to get ready to bang her. Butter shots are typically high in alcohol content, like doubles or everclear.
James: Man I want to get some
Dwayne: Dude you could bang that butter face ugly chick
James: I'll down a BUTTER SHOT or two, and I'll be ready to go