There was even an entire standards document drawn up (as a practical joke), called the Hyper Text Coffee Pot Control Protocol (HTCPCP 1.0). To this day though, there the server status response 418 - I’m a teapot still exists. It was defined as part of HTCPCP as the error code returned when you tried to get a teapot to brew coffee :)

Web nerds took their coffee seriously! Or maybe they didn’t? Does doing up an entire standards document as an april fools joke count as serious or unserious?

Nerds making joke standards is nothing unique.

See also: IETF RFC 1149 and IPoAC

Another example of such an attack

CW: animals being eaten

that’s not a man-in-the-middle attack (unless the bird is a trained falcon or something), it’s packet loss due to infrastructure damage