Help with translation

Hi, there!
I'd like to ask for help regarding the expression "Chic-or-treating".. I'm translating one book about some posh girls in US and I cannot figure out what this exactly means. I know "trick or treat" thing, but can anybody clarify to me the meaning of the first expression?

thank you very much

I've never heard of that expression.

People use "Chic" to describe something that's classy, fashionable, stylish etc.

If you're reading a book about posh girls than that might have something to do with it, but I don't know what book you're reading, thus I don't know how it would relate to the topic. XD

well, the girl plans to go to some Halloween party. In the meantime she makes a list of what's in and what's out and in the OUT column there's this expression chic-or-treating..and that's it..it's not mentioned anywhere else in the book, it's not a part of a sentence..ooooooh, I'm so frustrated with this:(