Place plastic cups on a small baking sheet (for easy transporting). Set aside.
In a small mixing bowl, sprinkle the gelatin powder over 1/4 cup water, and allow the powder to soak in for 2 minutes.
Add sugar to the boiling water and whisk until dissolved. Pour the boiling water into the gelatin and whisk until the gelatin is dissolved.
Add the pineapple juice, coconut syrup, and rum. Whisk to combine.
Pour jello mixture into prepared cups. Refrigerate uncovered for 30 to 40 minutes until jello had begun to thicken.
Remove jello from the fridge and place one cherry in the center of each cup. Press gently down to partially submerge the cherry. Refrigerate until completely set, about 2-3 hours.
Cover each cup with a lid and refrigerate until ready to serve.