Pour 4 2 liter bottles Mountain Dew into a clean, sanitized brew bucket. (The soda should not have anything growing in it, so there's no need to boil. Let it sit in the bucket (covered) as you boil the wort so the level of carbonation will decrease.) Bring 2.5 gallons (9.5 L) of water to a boil and stir in malt extract. Boil for 60 minutes, adding hops at the times indicated in the recipe. Add Irish moss with 15 minutes left in the boil. Cool wort and pour into Mountain Brew. (Watch for excessive foaming.) Top up to 5 gallons (19 L) with water. Aerate (again, watching for excessive foaming) and pitch yeast. Ferment at 68 °F (20 °C) for 1 week. Rack to secondary and age for 2 weeks, Bottle with corn sugar.