Pop your popcorn as desired. Air-popped is best, but butter-free microwave popcorn works.
Spray a cookie sheet with cooking oil and set aside.
Place the corn syrup and white sugar in a small saucepan over medium heat. Stir continuously, until the white sugar is completely melted and the mixture takes on a caramel appearance, about 3-4 minutes.
Add the Peanut Butter and stir in completely. Continue to cook for one more minute before removing from heat.
Immediately pour the Peanut Butter mixture over the popcorn and stir to coat completely.
Spread the Peanut Butter popcorn over the cookie sheet in a single layer. Let set for 4 hours or overnight until no longer tacky to the touch.
Break up the Peanut Butter popcorn and store in an airtight container until ready to serve.