aquas frescas (sandia)???
Hmm, I haven't ever seen a watermelon aqua fresca but, I'd be anxious to know as well. Sounds delicious.
Most of the (real) Mexican places I eat at serve a delicious hibiscus aqua fresca called, jamaica. The "j" is pronounced like an "h". If you see it, order it. I love the hibiscus aqua fresca served at Sea Shack (had one there today) and El Tizoncito in Oak Cliff.
El Ranchito on Jefferson Avenue in Oak Cliff serves a delicious watermelon Margarita. Maybe........
610 W Jefferson Blvd, Dallas, TX 75208