In a small bowl, mix the boiling water and lemon-flavored gelatin. Stir until dissolved. Add the vodka to the mixture and stir well to combine. Allow to cool for a couple of minutes, and pour into shot glasses to fill ⅓ of the way.
Refrigerate until set, about 90 minutes.
Make the Orange Layer:
In a small bowl, mix the boiling water and orange-flavored gelatin. Stir until dissolved. Add the vodka to the mixture and stir well to combine. Allow to cool for a couple of minutes, and pour into shot glasses to fill ⅔ of the way.
Refrigerate until set, about 90 minutes.
Make the White Layer:
In a small bowl, mix the boiling water and unflavored flavored gelatin. Stir until dissolved. Add the vodka and condensed milk to the mixture and stir well to combine. Allow to cool for a couple of minutes, and pour into shot glasses to fill.