Cook cake according to box directions (usually water, oil, and eggs are needed). Let cake cool for 15 minutes.
Combine Jello / gelatin mix with 1 cup boiling water. Choose your flavor - we used strawberry.
Poke holes in cake with a fork or with the back of a wooden spoon. Make sure holes are all over cake.
Pour Jello / gelatin mix mixture over the cake evenly.
Spread Cool Whip on top of the cake. I personally like to use fresh whipped cream (heavy whipping cream and sugar) instead of Cool Whip. Garnish with fruit.
Allow cake to refrigerate for 3 hours before serving to allow it to cool and set.