In a medium saucepan, stir together tonic water and sugar until sugar dissolves. Sprinkle gelatin over top and let rest for 5 minutes until the surface is wrinkled.
Place the saucepan over the stove on medium heat. Warm the liquid over medium heat for 2 to 3 minutes, stirring until gelatin is completely dissolved. Do not let boil. Remove from heat.
Whisk in the limeade, vodka/gin and lime juice.
Distribute into 12 plastic shot glasses. Refrigerate 3 to 4 hours before serving. Keep chilled until serving. Top with sprinkles before serving.