Across between a milk shake and a dessert, this refreshing cooler is sold at street stalls and markets throughout Southeast Asia. Sweetened condensed milk is the dairy product of choice here because it will not spoil in the tropical heat. Feel free to vary the fruits.
Working in batches, combine the watermelon, diced strawberries, bananas, lime juice, sugar, condensed milk, and ice in a blender and blend until smooth. Taste for flavoring, adding more lime juice and/or sugar as necessary. Serve the coolers at once in 6 tall glasses garnished with the whole strawberries and straws.