Starters for/to muses who have never heard of, or experienced, Halloween (the anon request was for non-human muses, but I feel this can be attributed to several situations.)

“It’s just a costume, don’t worry. We don’t actually shape-shift into monsters on Halloween night.”
“I’ve never heard of a holiday like this before.”
“There’s candy? I guess it can’t be that bad then.”
“I can’t believe you’ve never heard of Halloween before!”
“What kind of childhood did you have if you never ate Halloween candy?”
“Amazing. They shaped the peanut butter circle into a small pumpkin. How extraordinary.” 
“There are whole parties where everyone is dressed up like something else? How do you recognize anyone?”
“Uh, no, there aren’t any human sacrifices. They got rid of that a few centuries ago, I think.”
“You’ll love Halloween! It’s much better than Valentine’s Day, I promise.”
“Why do you have to kill the pumpkins? You put a face on them and then they rot. Isn’t that a bit cruel?”
“Is there any kind of brutal punishment if I don’t wear a costume?”
“So what deities are they praying to when they dress up like zombie nurses?”
“This is without a doubt the strangest holiday I have ever heard of.”
“There’s not usually a significance to the costume, no. Just whatever you want to be!”
“A whole holiday all about being scared and contacting the dead? Have you all gone mad?!”
“I’ve heard of holidays like this, but never experienced it.”
“It’s a good excuse to hang out in the cemetery and not look too suspicious.”
“No, we don’t just wear costumes or watch scary movies. We also egg peoples’ houses and throw toilet paper on their yard. We’re classy like that.”
“This is the only night you can contact the dead? Where I come from, we do that every day.”
“I think I like this holiday so far.”
“I’m not sure I like Halloween.”
“Don’t worry, Halloween is overrated anyway.”
“Costumes and candy are for babies. You and me? We’re going to raise the dead.”
“No, we don’t burn witches on Halloween. That’s so seventeenth century.”
“Black cats and pumpkins and stuff, it’s all just based on old superstitions and legends.”
“Tell me about the history of this holiday.”
“This isn’t one of those Santa Clause things, is it? I don’t want to know what kinds of presents he would bring.”
“Ugh! All of these costumes are hideous. And people dress like this for fun?”