Dennis Ritchie posted, sharing an extremely early version of a C compiler. Richard Heathfield (well known C book author) jokingly chided Ritchie for posting something off-topic, as it was not part of ANSI C. In typical Usenet fashion, this triggered a huge thread, arguing over the appropriateness of the joke. Even Linus Torvalds got involved.
Apparently Heathfield emailed Ritchie privately to apologize, and Ritchie's response is well known to anyone in clc: "Usenet is a strange place."
Original thread: https://groups.google.com/g/alt.folklore.computers/c/wbzzoyS... (I believe it was crossposted to clc)
Some discussion of the saga: https://en.wikiquote.org/wiki/Talk:Dennis_Ritchie
RIP dmr