Fun Fact and History Lesson!
The 'no beta we die like [character]' originated from this damn photo that went viral on Tumblr in 2016 and changed Ao3 tags and fanfic vernacular forever.
Meaning: it's a tag used on fics that were not beta read (the author didn't get someone to read it for them before posting). Betas read fics to check for spelling, grammar, consistently, etc and often edit it.
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Similarly, 'Dead dove' or 'dead dove do not eat' is from this scene in Arrested Development.
Meaning: if there's a warning of something really dark/bad, don't open/read it and expect something different. Or: 'mind the tags this is dark, don't read if you don't like it'.