Preheat oven to 350 degrees and coat a 13x9 baking dish with non-stick cooking spray
Combine cake mix, eggs, buttermilk, and oil until smooth.
Spread evenly into baking dish, bake for about 25 minutes or until a toothpick inserted in the center comes out clean
Remove from oven and let the cake cool for 15 minutes
Combine gelatin and boiling water and stir about 2 minutes until dissolved, add cold water
Using a wooden skewer or large fork, poke holes into cake about every 1/2 inch
Carefully pour gelatin over the cake
Place in refrigerator at least 3 hours or overnight
Frosting
In a mixing bowl, combine whipped topping with pudding mix until completely smooth
Spread over cake
Store in refrigerator until ready to serve
Store leftovers in refrigerator covered with plastic wrap
Serve with sprinkles or fresh limes