I'd guess the idea would be to pass around a copy of Hamlet, the Odyssey, Canterbury Tales, KJV Bible[1], or a similar public domain lengthy and popular work that would, in itself, draw no attention to itself.

For me, the reason I always hesitated to use widespread encryption ahead of mainstream adoption was that standing out as an oddity seemed to pose a greater threat than taking no extraordinary efforts. That is, if I engaged in behavior similar to someone with good reason to hide then I might become a target for scrutiny. My "opsec" wouldn't have been effective for anything beyond casual scrutiny, so my security efforts would have been demonstrably counter-productive[1]. At least that was my logic. A couple examples: as soon as full disk encryption started shipping with Windows, I used it. When choosing between SMS, Hangouts, and iMessage, I'd choose iMessage.

Not saying my logic was sound, but feel confident that it contains at least a degree of truth.

[1] Sort of an all-or-nothing choice. Taking some steps arguably makes you a higher profile requiring consistent security measures taken at every turn.