Putting it together:
Drain pineapple juice into a medium bowl; set pineapple aside, add sliced bananas to the juice and set aside.
In a large bowl, combine cranberries and sugar, remove bananas from juice and discard juice (or drink it if you want) add bananas to the cranberries, stir in pineapple, whipped topping and nuts.
Pour into a 13x9 in dish and freeze until solid.
Remove from the freezer about 15 minutes before cutting and serving.
You can refreeze what is leftover but it will only keep for about 4-5 days and then the bananas start turning dark.