This is a drink my grandmother made in the summertime for quick rehydration. Kind of an early version of the -ades that do that these days.
1 large egg, beaten
3/4 cup sugar
1 to 2 tbsps ground ginger (to taste, I use 2)
1/2 tsp salt
2 to 3 tbsps cider vinegar (must be cider, not white!) (again, to taste, you don't want it too vinegary, but if you mis-measure the sugar you may need more)
2 quarts ice cold water
Mix the first 5 ingredients thoroughly and add to the water stirring slowly. Taste and add more vinegar as needed.
You have to mix the ingredients into the water, not the water into the ingredients, or you'll get a lot of froth. Not that I have anything against froth, I just do it the way grandma did.
Serve over ice. Lay back in a hammock, relax.