Add the pineapple juice and vanilla vodka to a cocktail shaker with ice. Shake until very cold. Strain into a tall shot glass.

Pour a tiny bit of grenadine down the inside of the shot glass, over the back of a spoon. Do this very slowly. The grenadine should settle on the bottom.

Cut a small slit into the bottom of a maraschino cherry and sit the cherry on the rim of the shot glass.