In a mixing bowl, stir 1 cup of boiling water with the cherry jello crystals until the gelatin crystals have dissolved, about 1 minute.
Add ⅔ cup Fireball whiskey and ⅓ cup cold water.
Mix again.
Pour into shot cups, filling them about ¾ full.
Chill in the refrigerator until set, 2 to 4 hours.
Notes
The cookie sheet makes it much easier to transport the jello shots in and out of the refrigerator.
Adjust the amount of cold water and Fireball whiskey based on how strong you want your jello shots to be. Just make sure that the combination of the two comes out to 1 cup of total liquid.
Using a mixing bowl with a spout will make it easier to pour the jello mixture into the shot cups.