Prepare 5 shot glasses. Add one stemless maraschino cherry to the bottom of each. Distribute the grenadine evenly among the 5 shot glasses.

Add the pineapple juice and cake vodka to a cocktail shaker with ice. Shake to combine.

Place the back of a bar spoon right above the cherry layer and slowly strain the vodka mixture over it to keep the layers separated. 

Serve immediately.