Board Thread:News and Announcements/@comment-37272354-20181203232212/@comment-26618197-20181205121727

It's not grossout humor because he was clearly distressed and nothing about that scene was humorous, besides the show doesn't do grossout humor. It's common in animation for something resembling a fear, regret, or desire of a main character to come out of the person's body in a dream. Though it's not normally through the mouth, it's often through the forehead or heart to represent a burden on their mind or heart, or sometimes through their shadow to represent where their demons hide.