Combine the vodka and pineapple juice in a cocktail shaker and give a shake to combine.
Pour equally into 6 shot glasses.
Using a cocktail spoon, gently pour ⅙ ounce grenadine into each shot. I use a jigger to pour as it pours the cleanest.
Garnish with a maraschino cherry, if desired, and enjoy!
To Make One Shot:
Pour the vanilla vodka and pineapple juice into a shot glass.
Using a cocktail spoon, gently pour the grenadine down the side of the shot glass.
Top with a maraschino cherry, if desired, and enjoy!
Notes
If you want to prepare these ahead of time, I suggest holding off on adding the grenadine until you're about to serve them. Otherwise, they will just appear red without the distinct layers of color in each shot. You can combine the vodka and juice and keep them in a sealed container in the refrigerator for up to 4 days. Only add the grenadine right before serving. These shots are most delicious when enjoyed immediately.
I usually make sure to chill the vodka and juice in advance so they're just right when poured. But if you prefer them ice cold, just toss in a few ice cubes in the cocktail shaker before straining the shots.
To tone down the pineapple taste, just replace a bit of the pineapple juice with extra vanilla vodka.