RFC for the 7XX Range of HTTP Status codes - Developer Errors
At Railscamp X it became clear there is a gap in the current HTTP specification.

There are many ways for a developer to screw up their implementation, but no code to share the nature of the error with the end user.

We humbly suggest the following status codes are included in the HTTP spec in the 7XX range.

70X - Inexcusable
701 - Meh
702 - Emacs
71X - Novelty Implementations
710 - PHP
711 - Convenience Store
719 - I am not a teapot
72X - Edge Cases
720 - Unpossible
721 - Known Unknowns
722 - Unknown Unknowns
723 - Tricky
724 - This line should be unreachable
725 - It works on my machine
726 - It's a feature, not a bug
73X - Fucking
731 - Fucking Rubygems
732 - Fucking Unicode
733 - Fucking Deadlocks
734 - Fucking Deferreds
735 - Fucking IE
736 - Fucking Race Conditions
737 - FuckThreadsing
738 - Fucking Bundler
739 - Fucking Windows
74X - Meme Driven
741 - Compiling
742 - A kitten dies
743 - I thought I knew regular expressions
744 - Y U NO write integration tests?
745 - I don't always test my code, but when I do I do it in production
746 - Missed Ballmer Peak
747 - Motherfucking Snakes on the Motherfucking Plane
748 - Confounded by Ponies
749 - Reserved for Chuck Norris
75X - Syntax Errors
750 - Didn't bother to compile it
753 - Syntax Error
76X - Substance-Affected Developer
761 - Hungover
762 - Stoned
763 - Under-Caffeinated
764 - Over-Caffeinated
765 - Railscamp
766 - Sober
767 - Drunk
77X - Predictable Problems
771 - Cached for too long
772 - Not cached long enough
773 - Not cached at all
774 - Why was this cached?
776 - Error on the Exception
777 - Coincidence
778 - Off By One Error
779 - Off By Too Many To Count Error
78X - Somebody Else's Problem
781 - Operations
782 - QA
783 - It was a customer request, honestly
784 - Management, obviously
785 - TPS Cover Sheet not attached
79X - Internet crashed
797 - This is the last page of the Internet. Go back
799 - End of the world