I've always loved milk ;w; Crisp cold milk quenches my thirst in the heat. Juice is good too, l like apple juice and lemonade. I like ice cream, but it tends to be too sticky and makes me more thirsty. I think for food, I'd cool down with froyo. It makes me cold pretty fast!
There's nothing better than ice-cold water on a hot day!
I like eating warm food though, even in summer. I love grilling chicken, burgers, and hot dogs in summer! Plus I go to a big 10-day long fair every year and they have the absolute best mini donuts, and you've just gotta eat them when they're hot and fresh!
Fruit is also really great. Juicy, cool cherries and mangoes are the absolute best!