In a large pitcher, combine 4 cups of cold water, 1 cup of freshly squeezed lemon juice, and 1 cup of granulated sugar. Stir vigorously for about 2-3 minutes until the sugar completely dissolves.

Once the sugar has dissolved, slowly incorporate 1 teaspoon of activated charcoal powder into the pitcher. Gently stir for 1-2 minutes until the lemonade transforms into a deep black color.

Carefully pour in 1 cup of chilled soda water and gently stir for about 30 seconds to blend without losing the carbonation.

Slice fresh lemons into thin rounds for garnish, preparing about 6-8 slices.

Fill tall glasses with ice cubes halfway. Pour the prepared lemonade over the ice, filling each glass to the brim.

Place a few gummy worms or candy eyeballs on top of each glass as a whimsical garnish.