Chances are they've already shoved some app on their phone that's voice to txting everything they say and sending off somewhere (well lower chance if they have an iphone).
Modern life is data/information security and humans are insanely bad at it.
I don't think it's a problem to find a word or a sentence or a story - whatever - that's commonly used by everyone on daily basis but in different context. That's not a problem by itself :) try it
For the idiots, it is still possible to find a word. They may be idiots, but still, they work and live on their own. They coming along in life. So, it's up to the smarter one to find a no-brainer solution.
I am confident and believe nothing and no one is stupid enough not to be able to adapt to something. Even if it's me, who'll need to adapt to members with less brain.
This is my biggest gripe against the telecom industry. Calls pretending to be from someone else.
For every single call, someone somewhere must know at least the next link in the chain to connect a call. Keep following the chain until you find someone who either through malice or by looking the other way allows someone to spoof someone else's number AND remove their ability to send the current link in the chain (or anyone) messages. (Ideally also send them to prison if they are in the same country.) It shouldn't be that hard, right?
The technology to build trustable caller ID has existed for a long time, the problem is no one wants to be the one forcing telcos all over the world to upgrade their sometimes many decades old systems.