[mhink]

This always reminds me of a great find I discovered a while back when I was reading the HTTP/2 RFC for whatever reason.

Back before "429 Too Many Requests" was standardized, Twitter's API used to return a nonstandard 420 status code (with the caption "Enhance Your Calm") when rate-limiting incoming requests. They stopped doing this for understandable reasons, but the caption, at least, got snuck into HTTP/2, see:

https://datatracker.ietf.org/doc/html/rfc7540#section-7

down at 0xb, the caption for disconnection due to excessive load is, indeed, ENHANCE_YOUR_CALM. Always makes me smile. :)