Prepare the cake mix in a 9x13 pan as per the instructions on the box. Bake until golden and a toothpick inserted in the center comes out with only a few crumbs (not wet batter). Allow the cake to cool for 15 minutes after removing it from the oven.
In a medium-sized bowl, combine the strawberry jello mix with 1 cup of boiling water. Whisk for 2 minutes, or until the powder is completely dissolved. Whisk in 1/2 cup of cold water and set aside.
Repeat the process in a second bowl to prepare the lime jello.
Using the handle of a wooden spoon, poke holes throughout the top of the cake.
Spoon or pour the prepared jello mixtures into each of the holes, alternating the colors as you go.
Refrigerate the cake for at least 3 hours to allow the jello to set.
Frost the cake and top with sprinkles before slicing and serving.
Notes
Store leftovers covered in the refrigerator for up to 3 days.