I generously thought maybe the couple didn’t understand what cocktail attire actually ment but the chances that all the rest of the guests interprited it to mean the same standard of dress is extreamely unlikely. I would be interested to see the wording of the Knight Templar Ugly Sweater. Although obviously if the groom & bride said anything verbally there would be no record.
Knight Templar Ugly Sweater, sweater, hoodie, and t-shirt
I once showed up to a friends wedding in a Tux because the invite said Black Tie. I showed up and the mother of the bride was really confused as to why I was in a Knight Templar Ugly Sweater and thought I was being a weirdo or trying to show everyone up. Luckily my friend thought it was funny when she realized she didn’t really know what black tie meant and that I owned a tux. What she actually wanted was just formal so all the men in suit jackets and ties.
Best Knight Templar Ugly Sweater
Oh it’s SUPER weird. But assuming it’s not a work of creative fiction, OP is NTA. She couldn’t have known that the cousin she had never met before being inexplicably invited to Knight Templar Ugly Sweater , had put “cocktail attire” on her invitations without having the faintest idea what that actually meant. (Although advanced etiquette would recommend making any minor alterations you can once you realize you’re overdressed .