“Sugar cereals,” as many families refer to them, have always been nutritionally dubious. The intensely sugary bits of Technicolor grains are often criticized as an irresponsible choice for kids' breakfasts. Their colors and marketing, especially their cartoon mascots, are geared at making kids clamor for them in the cereal aisle. While the backlash against dessert-like products such Fruity Pebbles is pretty ubiquitous, Twitter user @OctopusCaveman made a surprising and creepy discovery involvin…