5 (1.5 fluid ounce) jiggers vodka
4 (1.5 fluid ounce) jiggers gin
3 cubes ice
2 (1.5 fluid ounce) jiggers pale dry sherry
1 1/2 fluid ounces water
Pour vodka, gin, ice cubes, sherry, and water into a glass container and freeze until mix is slushy, at least 3 hours. At the same time, freeze martini glasses.
Pour martinis into glasses, straining out any remaining ice cubes.