I will admit that I worry about what to wear to various book events. But I don't worry about what costume to wear to a party launching one of my books, because it ain't never going to happen. If I ever have a book launch party, which seems unlikely, I will worry about what to wear. But I already know that it won't be a costume.
I have to admit, though, that as a result of reading about this party and seeing this author's picture, I did try to find information on her, and I may remember the name of her book.
I'm still not wearing any costume.
Thanks to ACHOCKABLOG for the picture.