Add the limes, sweetened condensed milk, granulated sugar, and cold water into a blender.
Blend for two short 8 seconds pulses. There should be medium chunks of lime skin broken apart. If you blend too much, the drink will taste bitter.
Pour the mixture through a fine mesh strainer to remove the chunks of lime. Rinse out the blender.
Pour the mixture back into the blender. Add in the frozen pineapple, cream of coconut and ice. Blend until frosty and smooth. Pour the drink into glasses and garnish with a maraschino cherry.
If you want to spike the drink, add 1.5 oz. of light rum to each drink. Enjoy!