I honestly thought it was all about embellished sweaters that may actually be sweatshirts. But I much prefer the idea of borrowing one of any style that's already in the family, or just decorating yourself with garland, lights or whatever... something creative rather than purchased!
Apparently Value Village is promoting the concept hard, so maybe that's part of the reason these parties are catching on in Canada. At least they do have some DIY versions.
https://www.valuevillage.com/i.....ckysweater
Jaileen, I think your sweater is actually cute, but totally acceptable to wear to such a theme party (and I like the fact the other guests saw it as a request rather than a demand and basically said a polite "no thank you!").