Remove the liquid from the pickle jar, saving in a small mixing bowl or glass measuring cup.
Stir in the Kool-Aid mix and sugar until dissolved.
Pour the liquid back into the pickle jar with the pickles (it may not all fit as there will be more volume after adding the sugar).
Store the pickles in the refrigerator for at least seven days. Every few days give the jar a shake to make sure no sugar or sediment stays on the bottom.
Notes
You can use any flavor/color of Kool-Aid for this recipe. I've noticed the red and orange colors tend to soak in better than blue or purple colors. The longer you allow your Kool-Aid pickles to soak (past the first seven days) the deeper the flavor.