I hadn’t heard of code 418 before - seems like it started as a joke but is now “real” because people use it!
All the April Fools RFCs are worth a read imho [2]. RFC2100 (The Naming of Hosts) and RFC8135 (Complex Addressing in IPv6) are real gems.
1: https://datatracker.ietf.org/doc/html/rfc2324
2: https://en.wikipedia.org/wiki/April_Fools%27_Day_Request_for...
I myself use 418 as a reply to mean bots. Fun + makes filtering logs easier.
Nginx config snippet:
# Nothing to hack around here, I’m just a teapot:
location ~* \.(?:php|aspx?|jsp|dll|sql|bak)$ {
return 418;
}
error_page 418 /418.html;