I think I have explained to them here... on another website I also use them but I haven't explained them there and it's fun to screw with them :3
that is a cookie. it is what I consider to be the representation of happiness and health. avocados are delicious and wholesome and sushi is too. they have a special place in my happy (that totally made sense XD). I call it a cookie as a joke about my personality. I don't always make sense to other people and this is a play on that. it also is because I find cookies, like sushi, a gift. a small package of perfection. smaller than a cake, bigger than a gummy thing, and deliciously sweet or savory. it fits everyone as far as I know. I use it as an adjective of sorts, the same way I have made "kitty" synonymous with "cute".