IT MIGHT MAKE YOU FEEL SICK, BUT IT CAN'T KILL YOU
In an apparent study by Vouchercloud, 10% of folks in the US supposedly think that HTML is an STD. This fired up my imagination:
411 (Length Required) is a common issue. This often correlates with 416 (Requested Range Not Satisfiable), which may lead to 417 (Expectation Failed).
413 (Request Entity Too Large) is error 411 in reverse, which correlates with 306 (Unused).
An attempt at 101 (Switching Protocols) may return 400 (Bad Request), 405 (Method Not Allowed), 402 (Forbidden), or 406 (Not Acceptable).
Repeated attempts may cause suspiciously frequent future occurrences of 503 (Service Unavailable). This may in turn lead to 409 (Conflict).
303 (See Other) is the result of a "GET, HEAD" request that fails once too often within a 300 (Multiple Choices) environment, leading to an error 410 (Gone), or a 301 (Moved Permanently) situation.
401 (Unauthorised) may occur if 412 (Precondition Failed) applies, and social protocols have not been followed. One may skip these protocols entirely with 305 (Use Proxy), seeking an alternate gateway that presents the status code 402 (Payment Required), whereupon the client should continue with its request.