Pop your popcorn of choice and set the warm popcorn aside in a large bowl.
In a small saucepan over medium heat, combine the corn syrup and white sugar. Stirring often, bring to a rolling boil. Once boiling, remove from heat and stir in the peanut butter and vanilla until smooth.
Immediately drizzle the peanut butter sauce over the popcorn and gently toss and stir until the popcorn is completely coated with the peanut butter sauce. Eat immediately for soft, chewy peanut butter popcorn!
If you're not using microwave popcorn with butter and salt, you may want to add a pinch or two of salt into the peanut butter sauce. Also, if you want a really gooey caramel popcorn texture, use less popcorn. Likewise add an extra cup or two of popcorn if you want it to be a little less chewy.