I'm probably wrong but I've always thought that "86" meant simply to dismiss something or scrap it while "deep six" is the one that means "send something or someone to the bottom of the rive/ocean/ etc.
FWIW, this is what Google AI says:
FWIW, this is what Google AI says:
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M-S-1-3. It says M-S-1-3 in the sand
https://bsky.app/profile/danarchy.bsky.social/post/3lpcqrfhbhs2l
But then again, I swear "out of pocket" referred one thing and one thing only: paying for something yourself when someone or something else should be paying. Now "out of pocket" means crazy or out of office or any of dozens of things. So who knows anymore.
That’s all it’s ever meant.