Who is "Cereal"?

Once upon a time, my youngest son was errantly called Cereal by a substitute teacher, who could not pronounce his name. Seeing that he is a skateboarding enthusiast, and some of the skaters he admires have nicknames like Bam, Benson, Blinky, Boo, Bucky, Dune, Gator, Holmes, Horsey, Jinx, Manchild, Mutt, Ollie, Pork Loin, Slomo, Sluggo, Spanky, Steak, Wee-Man, Yelawolf, Zorlac, etc. he decided to roll with it. 

Could be worse, I guess.🤷🏻But in many ways, his nickname became official when the some of his most-beloved skaters from Death Skateboards, his favorite skateboarding company, wished him a happy birthday, using his nickname of Cereal at https://www.instagram.com/p/CqPd6SEO2cX/.