The first full day we were in Jamaica, we asked one of our waitresses ("String Bean" read her name tag) what she recommended for a drink that was strong and wasn't too sweet. She suggested a Dirty Banana (which wasn't on the menu) and we said okay without asking what was in it - and it was perfect, and I drank about a million of them before we left, and I don't even like bananas.
I made sure to spy on how they made it and wrote it down for when I came home - although since they just tended to throw ingredients together without measuring, it's taken me some time to perfect the proportions. Naturally the next step was to share them with you, dear reader.
2 oz gold or dark rum (we've been using Appleton)
2 oz rum cream (the Caribbean version of Bailey's - we brought Sangster's back with us, but as it's not available in the States, you'll have to make do with whatever they have at Total Wine)
1/2 oz creme de cacao
1/2 oz simple syrup
1/2 ripe banana
Throw all ingredients in a blender. Add ice till the three cup mark; blend until smooth. Makes 2.