Line a baking sheet with foil and spray the foil with nonstick cooking spray.
In a medium saucepan, combine the water, corn syrup, and granulated sugar. Place the pan over medium-high heat, and stir until the sugar dissolves. Bring the mixture to a boil, then stop stirring and brush down the sides with a wet pastry brush to prevent sugar crystals from forming. Insert a candy thermometer.
Continue to cook the candy without stirring until it reads 285 degrees Fahrenheit (140 C) on the thermometer. Do not overcook it, or it will start to take on a caramel color and your candy might turn green! Once at 285, take the pan off the heat and let it sit for a few moments, until bubbles stop breaking on the surface. Add the flavoring and a drop of food coloring, and stir everything together.
Pour the candy onto the prepared baking sheet and tilt it so that it runs into a thin layer. Let it set completely at room temperature.
Once set, break it into small pieces by hand. For the complete “crystal meth” experience, place the pieces in a large zip-top bag and smash them with a rolling pin until they are crushed. Store the candy in an airtight container at room temperature.