Add the frozen pineapple chunks, coconut milk, and half the ice into your blender.
Blend on high until the mixture becomes thick, smooth, and creamy, with no ice chunks remaining. Pause occasionally to scrape down the sides if needed.
Add the remaining ice gradually and blend again until the slushie reaches a frosty, scoopable consistency. The sound should be loud and icy as the blender works.
If desired, stir in a splash of rum or lime juice to enhance the flavor, blending briefly to combine.
Pour the slushie into glasses, and if you like, garnish with a slice of pineapple or a sprig of mint for an extra tropical touch.
Serve immediately with a straw or spoon for a cool, icy treat that captures a tropical vacation in every sip.