Divide contents of blue jello into two bowls. Repeat for the red jello,
Divide sweetened condensed milk between two bowls (¼ of a standard 14 oz. can in each bowl).
Dissolve one portion of blue jello in ½ cup of boiling water. Stir until full dissolved. Stir in ½ cup of cold water.
Divide blue jello liquid across 6-8 clear cups.
Place cups into the refrigerator until fully chilled and the jello has set - about 1 hour.
For the white layer, combine 1 packet of plain gelatin and ½ cup cold water. Stir 3.5 oz. of sweetened condensed milk with ½ cup boiling water.
Stir together the gelatin mixture and the milk mixture. Pour an even layer of white jello over the blue layers in the cups.
Chill completely.
Dissolve 3 oz. red jello in ½ cup of boiling water. Stir until fully dissolved. Stir in ½ cup of cold water.
Layer red jello over the chilled and set white layers.
Repeat the previous steps for each layer until your cup is full. Be sure to chill thoroughly between each layer so that the layers don't blend together.
Top jello cups with whipped cream and sprinkles immediately before serving.