Good-Cooking - Confoundingly Cunning Cake

Ingredients

• 1 (18 ounce) box yellow cake mix (not pudding-in-the-mix, not butter-recipe mix)
• 1 (3.4 ounce) package coconut cream instant pudding mix
• 1 1/3 cup (most of a 12 ounce can) Mountain Dew
• 4 eggs
• 2/3 cup oil
• 1 teaspoon dried tarragon, crumbled finely