CW: racism, awful shit
There is a sense of the acronym "DNB" being used to refer to racist child gore shock content, which stands for dead + (hard-r) + baby.
Something like that should be documented as a definition, because for example if you see someone talking about how they "spammed DNB in someone's DMs" then you need to be highly aware of what they are referring to.
It's an abbreviaton used in O9A adjacent spaces for racist gore of children

Somewhat random reply, but 

American "experts" constantly being shocked about the most predictable thing ever is like those phone ads where they play the game as badly as possible