A Quick Fuck is a layered shooter made from one part coffee liqueur like Kahlua, one part cold Midoriliqueur and one part Baileys Irish Cream. The Baileys is poured off the back of a bar spoon so it "floats" on top of the Kahlua in a shot glass. Then slowly layer the Midori on top of the Baileys. Note that Baileys does not have to be used; any type of Irish Cream will do.
There are special machines that can prepare a Quick Fuck (or other multi-layered cocktails) in only a few seconds, but an experienced bartender usually relies on the traditional, handmade preparation. Cocktails with horizontal layering, like the Quick Fuck, are called "Pousse Café". This method of preparation is called "building," as opposed to blending or shaking; thus, Quick Fucks are "built."