The FBI Guide to Internet Slang
Pentagram does a snarky thing with a fun type design. Like Bierut, I wonder if any of these terms the FBI notes have ever been used by anyone. The idea of the document reminds me of the old Law Enforcement Guide to Satanic Cults. Link is to the film but its print predecessor baffled me even in middle school.
It speaks to the (uh, problematic) law enforcement mindset that there are dark forces and coded evils working in all corners of the world and they're the last bastion of defense against it. Too often those "evil" symbols are just non-WASP identifiers, and fear of youth comes from the same place — especially when so much of internet slang comes from AAVE and other non-white sources.