Put everything in a blender and blend until smooth. Serve immediately.
Notes
*Look for sweetened condensed milk in a squeeze bottle in the Hispanic food section of the grocery store. It's great to have on hand for when you just need a little.
Recipe by Crumbs and Chaos at http://www.crumbsandchaos.dreamhosters.com/2014/07/frosty-watermelon-limeade/