In a large bowl stir together the sugar and flour. Stir in the cheese. Add the drained pineapple chunks, and stir until the ingredients are well combined. Pour the mixture into the casserole dish.
In another medium bowl, combine the cracker crumbs, melted butter, and reserved pineapple juice stirrinw with a rubber spatula until evenly blended. Spread crumb mixture on top of pineapple mixture. Bake 25 to 30 minutes, or until golden brown. ENJOY!
P.S. I think this would be great if you added diced ham to it also.