So what's this 418 error? You may have noticed HTTP status codes like 404 (page not found) or 403 (forbidden). There are many other 4xx error codes, but 418 was only used for an Easter Egg. "This code was defined in 1998 as one of the traditional IETF April Fools' jokes, in RFC 2324, Hyper Text Coffee Pot Control Protocol, and is not expected to be implemented by actual HTTP servers." Here's the text from the document: "Any attempt to brew coffee with a teapot should result in the error code '418 I'm a teapot'. The resulting entity body MAY be short and stout."
{ via Search Engine Land }