Teapot - Talk:List of HTTP status codes - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Talk:List_of_HTTP_status_codes#Teapot
"Tsk! Status code "418 I'm a teapot" shouldn't be removed, it's from a real actual IETF blessed RFC. Albeit in the fine tradition of April 1st RFC"
RFC 2324 - Hyper Text Coffee Pot Control Protocol (HTCPCP/1.0)
http://tools.ietf.org/html/rfc2324#section-2.3.2
"418 I'm a teapot ... 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. "