Have you heard about the Sand Mandala? Well, it's this ritual where Tibetan monks create an intricately designed sand art. Then once it's completed, they would just sweep it away. Those weeks and weeks of meticulous hardwork gone in a single sweep.
That's pretty much what layering is. You spend time agonizing over each layer of spirit to ensure that the layers mix into each other, only to have it downed in less than a second.
So then, why bother layering your shots? Because it's bloody pretty, that's why.
It's actually pretty damn simple actually. All you need is a shot glass, a teaspoon and a spirit or 2, your favourite liquer, or 2. So let's just say we're making something called a Quick Fuck (no kidding). You'll need 1 part Baileys, 1 part Kahlua, 1 part Midori.
1. Fill 1/3 of the glass with the Midori first. The first and bottom part of the shot should always be the "heaviest" drink. By heaviest, I mean with the highest content of sugar so that it stays at the bottom. So the theory is that you fill it up with the heaviest first to the lightest. To have an idea which spirit is heavier than which this drinks gravity chart is a decent reference.
2. Grab a spoon. Front part facing up, touch the side of the spoon to the glass. Steady your hands. With the other hand, grab the Kahlua. Slowly, very very slowly, pour the liquid down the back of the spoon so that it flows to the side of the glass.
3. Do the same (and be EXTRA careful with this) with the Baileys.
Now enjoy how pretty it looks. Then proceed to down the shot.