It’s not a secret code or signal, but it is a punishable embarrassment if one is in the military. That punishment often involves leaving the flag up so everybody can engage in some light ridicule about whoever was too hungover to hang the flag properly. https://exemplore.com/news/navy-conspiracy-theory
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If a Navy sailor wanted to send a secret message to conspiracy theorists, this is not how they would do so.
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But it is fun to speculate.