You MUST listen to RFC 2119
https://ericwbailey.website/published/you-must-listen-to-rfc-2119/
This is pretty funny. I love when someone pays an artist just to bring something fun into the world. I do it now and again but we can always use more of that.
Art and fun aside, if you don't know RFC 2199, now's your chance to learn one of the most influential RFCs ever written.
Already know that one by heart? Do you know about the related RFC 6919?
If you already know both of those, well then perhaps I could interest you in RFC 3339, what people usually mean when they say ISO 8601.
I could go on, but I won't.