When you destroy a Hydronic Foodpod (giant food item: - Cheese Puff, Ravioli, Strawberry, Sugar Cube or scoop of Ice Cream) it will leave behind some glowing collectibles, these get tallied up at the end of each level and fill up a big pot which is split in to 15 segments. Once you have collected enough of these to fill a segment, you can choose to upgrade one of your 5 weapons of mass consumption! As soon as you've upgraded one, the achievement is yours.