You, of course, would never be the sort to play silly pranks on harried editors. But if you were that sort, you might try sending an email to the editor at Penguin Random House who is responsible for the backlist:
I found a very embarrassing error in your edition of Finnegans Wake by James Joyce. It is on page 267. I will not repeat it, but it will be obvious the moment you see it.
You would—hypothetically, if you were the sort to play silly pranks on harried editors—send that off and never respond to any messages sent in reply.