TIT (today i teach): you can use https://www.urbandictionary.com/ to explain new words of phrases.
in firefox (and many other browsers too), you can right click the search bar and "add search engine", and you can add a "keyword", i personally use "ud", and then i can type "ud dni" (for instance) in the address bar (ctrl+l to get there quick) and it goes straight to results
if the page isn't supported, it doesn't show "add search engine", google translate for example, you can still add it in a different way
search for a recognisable word, and bookmark the resulting page. then go to bookmark/manage bookmarks (ctrl+shift+o), find the bookmark, replace your recognisable word with "%s", add a keyword (depending on the language i use 2en, 2de, 2jp etc)
No. Double negative rules apply to modifying a negative, but in this context the first DNI should not be considered a negative but a noun in its own right.
First DNI: Men, do not interact with me.
Second DNI: Do not interact with me, misandrists.
The second is not literally the same thing as "men, interact with me" but it can be assumed to mean "I don't have a problem with men interacting with me." It is still is not a request for the interaction itself which is what double negative rules would imply.
Tl;Dr double negative rules in English simply aren't the same as they are in Latin which is why it's a fake rule, even beyond the usage for emphasis in casual speech.
I wonder if they knew or if they remained polyclueless