Toss the pineapple with the rum in a bowl and let stand for 5 minutes.
Microwave the white chocolate and coconut oil in a microwave-safe bowl until fully melted.
Microwave the popcorn according to the package instructions. Transfer the popcorn to a large bowl, pour the white chocolate mixture over top and mix to fully coat. Add the macadamia nuts, coconut and rum-soaked pineapple and stir to combine.
Pour onto a parchment-lined baking sheet and let set up in the fridge 5 to 10 minutes.
Omit the rum for a kid-friendly snack.