That's a bit of a running joke. It's funnier in the working draft PDFs of the standard, e.g.: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n429...

I've first seen this in some GCC internals document [1] in 2008. There "incomplet" was incomplete and "incorrekt" was incorrect.

[1] https://gcc.gnu.org/onlinedocs/gccint/Deficiencies.html

I'm not sure if this is a completely intentional joke or actually mojibake—if encoded as Latin-1 and decoded as UTF-8, you get "pµøoorly formatted."