A very certain distinctive of JWs is how they refer to themselves. "One of Jehovah's Witnesses". It's one of those coded jargon thingies. An outsider will say "a Jehovah's Witness", or even worse (to the JW ear) "a Jehovah Witness". Even though I am a very well informed outsider, I'll never dignify their delusion nor stroke their ego by saying "Are you one of Jehovah's Witnesses?" or "You're one of Jehovah's Witnesses".
In JW circles their own urban legends will have outsiders referring to them by their own preferred reference. You'll see anecdotes on Reddit, Quora and in videos where Joe or Jane Public came up to one and said "Are you one of Jehovah's Witnesses?" Upon reading/hearing this, I'll roll my eyes and say: "No they didn't!, They asked: (if the story is even remotely true, that is) 'Are you a Jehovah's Witness?' or 'Are you a Jehovah Witness?'" We outsiders quite simply don't use their jargon of self importance.
I assume exes drop the "One of ..." epithet very quickly as well?
While writing this the thought came to me about when that self-descriptor first came into being: was it part of the initial name change by Rutherford, or was it a later development? When is the first recorded incidence of "One of Jehovah's Witnesses"?