Preheat oven to 325° and line two cupcake pans with cupcake liners.
In a large bowl using a hand mixer, mix cake mix with crushed pineapple, vegetable oil, and eggs. Beat at medium speed for 2 minutes.
Pour batter into prepared cupcake pans and bake for 20 to 22 minutes or until a toothpick inserted in center of cupcake comes out clean.
Transfer to a wire rack and let cool completely before frosting.
In a large bowl, combine butter, 2 cups powdered sugar, pineapple juice, and vanilla. Using a hand mixer, beat until smooth.
Add remaining 2 cups powdered sugar and beat until light and fluffy.
Transfer frosting to a pastry bag fitted with a large star tip. Swirl frosting onto cooled cupcakes.
Garnish each cupcake with a pineapple wedge and a decorative straw.
