Line a baking sheet with parchment paper. Set aside. Preheat the oven to warm or 175 F. Place the popcorn on a large rimmed cookie sheet and place it in the oven to keep warm.
In a large saucepot, melt the butter and large marshmallows together over medium-low heat. When the marshmallows are completely melted, gently stir in the popcorn and graham crackers, and mini marshmallows. Remove the chocolate chips from the refrigerator and quickly stir them into the mixture. With buttered hands, form the mixture into balls the size of baseballs. Set each ball on the prepared baking sheet to cool.
Makes about 12 popcorn balls, depending on size