Ultra-Creamy Avocado Smoothie

Blend the milk, sweetened condensed milk and ice in a blender until very smooth. Add the avocado flesh and blend again until smooth. The mixture will be quite thick; add cold water a few tablespoons at a time, blending after each addition, until the mixture is pourable. Taste and add more sweetened condensed milk if you want it sweeter. Serve in chilled glasses with straws.