It's hugely popular in Berlin thanks to the large Turkish population, and ridiculously refreshing and satisfying.
I made a pitcher today with full fat Danone plain yogurt, but unfortunately didn't have any mint around, which adds another freshness dimension.
I can't believe I never made it at home before -- so easy:
1 pint of yogurt
1 pint of cold water
pinch o'salt to taste
(fresh mint if you have any)