"[He] doesn't want to get out of the car. He's afraid of what people will say and do to him. I convince him to go inside. He halts at the door. He's visibly nervous. I chalk it up to him being a bit of a worrier in general. Seriously, WHO WOULD MAKE FUN OF A CHILD IN A COSTUME ON HALLOWEEN?" she writes.
When she got inside, she realized that her son had perhaps understood why there was reason to be nervous.
"Two mothers went wide-eyed and made faces as if they smelled decomp. And I realize that my son is seeing the same thing I am," she writes in the blog. "And Mom A says in disgust, 'Did he ask to be that?!' I say that he sure did as Halloween is the time of year that you can be whatever it is that you want to be. They continue with their nosy, probing questions as to how that was an option and didn't I try to talk him out of it. Mom B mostly just stood there in shock and dismay."
The mother said it was "heart-breaking" to see the other parents judging her child.
"My job as his mother is not to stifle that man that he will be, but to help him along his way. Mine is not to dictate what is 'normal' and what is not, but to help him become a good person," she writes. " I hope I am doing that."
She told ABC News that her son was not necessarily nervous because he was dressed up like the female cartoon character, but just because he would be nervous dressed up as anything.
"I don't belittle those nerves, but I also don't blow them up either," she said.
The popularity of the blog post certainly seemed to be a surprise to Sarah, who posted this two days before Halloween, but after she first posted the picture of her son:
"I'm trying to decide if I want to post a little bit more about this. I'm on the fence if I should just let some things go or if I want to go into more detail. Do the two of you that read this have an opinion?"
Before she posted the picture of her son, one of her most popular posts had 15 comments.