1. Place lemonade and cranberry juice in separate large heatproof bowls and sprinkle 1 envelope of gelatin over each. Let stand until gelatin blooms, about 5 minutes.

2. Pour 1 cup hot simple syrup into lemonade and stir until gelatin is dissolved. Pour remaining 1 1/4 cups simple syrup into cranberry juice and stir until gelatin is dissolved. Divide vodka evenly between juices and stir to combine. Stir lemon juice into lemonade mixture.

3. Place plastic cups on a rimmed baking sheet. Divide juices evenly among cups. Refrigerate until set, at least 8 hours. Jiggle shots can be made and stored, covered, in a refrigerator for up to 1 week.