This one is improvised from a recipe I found in a rather humorously named website.

Take two slices of lime in a muddling glass and throw in a spoonful of sugar in it. Muddle it very well. Add ice to it. Pour two ounces of rum and four ounces of guava juice in it and then shake it well.

Pour it in a glass of your choice (I used a margarita glass) and serve.

Great tropical drink. Probably more suited to summer days but I enjoyed it anyways.