Heat oven to 375°F. In small bowl, mix coconut and granulated sugar.
Dip tops and sides of biscuits into melted butter, then into coconut mixture. On ungreased large cookie sheet, place biscuits, coconut sides up, 2 inches apart. Sprinkle any remaining coconut mixture over tops of biscuits.
Bake 14 to 18 minutes or until biscuits and coconut are light golden brown. Cool 5 minutes.
Meanwhile, in 10-inch skillet, melt 1/4 cup butter over medium-high heat; stir in 1/2 cup brown sugar. Cook until brown sugar is dissolved, stirring occasionally. Remove from heat; fold in bananas and rum.
In medium bowl, beat whipped topping ingredients with electric mixer on high speed until stiff peaks form.
To serve, split warm biscuits. Fill and top with filling and whipped topping.