I had one of these last weekend. I was pleasantly suprised how good it was. It tastes exactly like a piece of pineapple upside down cake. The bartender said the secret is Marshmallow vodka instead of vanilla, which is what most people use. I agree. :)
Pineapple Upside Down Martini
* 2 oz. pineapple juice
* 1 oz. marshmallow vodka
* small splash Grenadine
Put ingredients in a shaker with 2 ice cubes. Shake and enjoy.