In a mixing glass, combine Big Blue cream soda, vodka, and ginger ale (or lemon-lime soda). Gently stir.
Pour mixture into your cocktail glass.
Gently add your giant ice cube to the drink so that it does not submerse. Be sure to point the side with the concave indentation upwards to form a small well.
Pour grenadine into the ice cube's well to float the fake "blood."
Garnish with a maraschino cherry on a pick and enjoy!
Notes
Please note that the nutrition facts are subject to change based upon your choice of ingredients.