Coconana (Dark Rum with Bananas)

Gary and Mardee Haidin Regan love both piña coladas and banana daiquiris, so we combined the two. Dark rum is best, but light rum will suffice.

Combine the ingredients in a blender and 3whir on high speed until the mixture is thoroughly pureed.
With the blender running, slowly add more ice cubes, no more than three at a time. Listen carefully to the sound of the machine. When the machine resumes its normal pitch rather than sounding gravelly, look at the drink. You will notice a vortex in the center of the mixture. Keep adding ice until the vortex disappears and the mixture looks smooth.
Turn off the blender and stir the mixture with a long spoon or a chopstick. Replace the lid and turn on the blender. The vortex will reappear. Keep adding ice cubes, two or three at a time, until it disappears.