1. Line a baking sheets with parchment paper. Prepare a medium bowl of ice water. Put the popped popcorn in a large bowl.
2. Combine butter, corn syrup and brown sugar in a saucepan. Cook over medium heat, stirring constantly, until the sugar is melted and the mixture darkens, about 2 minutes.
3. Immediately pour the mixture evenly over the popcorn; gently mix with a spatula until well coated. Gently stir in the raisins.
4. Dip both hands in the ice water. Working quickly, press small handfuls (about 1/4 cup each) of the popcorn mixture into 2-inch balls, ensuring each ball is about even with Mariani Raisins. Place the balls on the prepared baking sheet. Let cool completely before storing. Store individually wrapped in plastic wrap in an airtight container.