These are the Cereal Monster Geeki Tiki mugs. Previously available at San Diego Comic-Con 2018, they're now available for pre-order from Entertainment Earth. $60 gets you the set of three including Count Chocula, Boo-Berry and Franken Berry mugs (no Fruit Brute or Fruity Yummy Mummy). Funnily enough, I just bought a box of Count Chocula at Target over the weekend. Prior I had told myself I wouldn't buy another box of cereal until I went a full week without seeing a cockroach in the kitchen, and I'm proud to announce I've given up on that dream.
Keep going for one more shot.
Thanks to Evan, who agrees there's nothing wrong with eating cereal out of a mug if you're too lazy to wash a bowl.