a version of pikachu, only made out of poop
little boy: mom look there's a pikachu
mom: no, son it's brown, that means its a poopachu
To be sad, upset, seriously depressed but with cuteness.
Eliza was excited to go to the movies with her friends. However, when they arrived, they discovered the movies were closed. Eliza pouted her lips and sighed, "Poopachu"