Squeeze the lemons (strain out seeds) into a cup and set to the side.
In a pot, mix 2 cups of water with the sugar, bring to a boil, then simmer.
Add the jalapeños and continue to simmer for 10 minutes.
Near the end of the simmering, add the cinnamon and stir.
Remove the chopped jalapeños from the sugar water.
Stir the jalapeño sugar water and the lemon juice into the gallon of water, stir or shake thoroughly.
Refrigerate for 30 minutes to an hour prior to serving.