Add the tonic water to a small saucepan. Sprinkle the Lime Jello on top.
Stir gently and let the mixture sit at room temperature for 5 to 10 minutes to bloom the gelatin.
After it sits, the mixture will look kind of gloopy and slushy. Don't worry -- this is perfect!!
Melt the Gelatin
Put the saucepan over low heat. We are NOT going to boil the mixture, but heat it just enough so that the gelatin will melt.
Stir as it heats up. The gelatin will melt at around 140°F (60°C). You will see that it turns from a slushy texture to liquid.
When the mixture is liquid and all the gelatin is melted, take it off the heat and let it cool for several minutes.
Add the Liquor and Chill
Add in the vodka and the triple sec liqueur and stir well.
Add the mixture to a squeeze bottle, a Jellinator, or any container with a pouring spout to portion out the shots.
Add about 1.5 ounces of liquid to each of your plastic shot glasses.
Put the shot glasses into the refrigerator for at least 2 hours to chill and set.
Once they are set, they're ready to serve! They should keep in the fridge for at least a few days.
Make them Glow
To get the best glow, serve them in a darkened room. Shine a UV blacklight on them to see the glow!
Notes
I first tested this recipe with Midori instead of triple sec, and the glow did not work! Definitely test it out if you are thinking of changing any of the ingredients. This is because some things, like salt and baking powder, will cause the fluorescence of the tonic water to stop working.