Not like this!
A very creepy shop window, in Woodstock, Vermont:
I can't remember what "poop" on the sweatshirt was supposed to mean. An acronym for something. Looking for "poop sweatshirt" on the internet, I found this and this.
Personally, I don't think children need to be dressed in a completely somber and dignified way, but, especially if they can't read, don't put words on them.