The gin fizz recipe in CocktailDB calls for fresh lemon juice, when she had recommended lime. I used lemon since I had half a lemon already cut. (As we learned this weekend, each lemon produces 2 oz. of juice.) The result tastes very like lemonade.
Shake together 1 oz. fresh lemon juice, 1 tsp. sugar, 1 1/2 oz. gin, and 3 cubes of ice. Strain into a highball glass, and fill with soda. Stir. Drink.