Pour 1 cup of vodka into a bowl.
Sprinkle 1 envelope of unflavored gelatin over the vodka.
Let it stand for a few seconds then whisk with a fork.
Add strawberry flavored Jello and whisk.
Pour 1 cup of boiling water in the bowl and whisk until the gelatin completely dissolves.
Pour the liqud in a heat proof measuring cup with a spout.
Spray the inside of the mold with cooking spray.
Close the skull mold and pour the mixture into the small hole at the top to fill each mold.
Let the jello set for 3-5 hours or overnight.
Slowly release the top of the mold and remove the jello shots.