A Dole Whip is a non-dairy ice cream like dessert. It's a lot like soft serve ice cream but lighter and tastes great and refreshing, especially the pineapple flavor. You can actually get a Dole Whip Float which is Pineapple Dole Whip in pineapple juice.
Dole Whips can be found at Aloha Isle which is just to the right after you cross the bridge from the hub into Adventureland.
I don't know if you'll be addicted once you try it, but you will probably want to get one on every trip to the MK like I do!