Stripe-It Rich Cake

1 (18.25 ounce) box cake mix (pudding included or not)
2 small boxes instant pudding (any complimentary flavor)
1 cup confectioners' sugar
4 cups cold milk

Prepare cake as directed on package, baking in a 13 x 9-inch pan. Remove from oven. Poke holes at once through the cake to the pan with the round handle of a wooden spoon; holes should be at 1-inch intervals.

Combine pudding mix with sugar in a large bowl; gradually stir in milk. Beat on low speed of electric mixer for not more than 1 minutes. Quickly, before pudding thickens, pour about 1/2 the thin pudding evenly over warm cake and into holes to make the stripes. Allow remaining pudding to thicken slightly, then spoon over the top, swirling it to "frost" the cake. Chill at least 1 hour. Store cake in refrigerator.