Best thing for it: makes you sweat, cools you down.
But if you sweat, you need to replenish your fluids. Personally, two litres of anything in one sitting is too much for me. But when I lived in the Mojave Desert it was not uncommon for me to drink a gallon of unsweetened iced tea a day.
I have heard the idea of drinking hot drinks to cool down, and although I’ve done it I prefer a half-litre or litre of something iced.
FWIW there was a front page story in the US edition of the Wall Street Journal on Tuesday about an American who has started an ice cube supply business in Germany, meaning he supplies those 5 lb bags of cubes or crushed ice to gas stations and supermarkets, who sell them to their customers.
His business has been booming during the heat wave, in spite of the resistance he initially encountered among retailers.
Hah! Welcome to MY world, you kraut-eaters!
(Mmmmmm, kraut! A friend was talking about a restaurant that sold homemade sauerkraut the other day–I must go. That’s something you just don’t want to make from scratch in your own house.)
Just wondering. Have the lighter beers that are intended to be drunk ice cold, like Pilsner, been more popular in Europe this summer? Nothing quite like a cold beer on a hot day and the heavier ones like stout or porter just taste nasty when they are too cold.
Here in the UK some breweries have struggled to keep up with the demand for Lager and those beers meant to be drunk ice cold. Obviously people have switched to them (or are drinking more).
Which leaves plenty of those nice cool pints of bitter that I prefer, and which you can actually taste. 
V