Add a layer of marshmallow fluff around the rim of both glasses.
Press sprinkles, candy corn, candy eyeballs, and other Halloween candies all over the coated rim.
Add ice cream and milk to a blender.
Blend until smooth.
Pour the milkshake into the cups.
Top both with whipped cream.
Add Halloween sprinkles and red decorating icing "blood" drizzled on top.
Top with a festive straw and drink up!