My colleague is a senior C developer and he had a bad experience in his job assignment. He was developing applications for a real-time embedded operating system named "Buggy OS™". He had to implement workarounds to avoid using the standard C library in some cases. For instance the
memcmp shouldn't be used to test command-line argument because of obscure reason resulting in some bits were not checked. Instead he implemented its own function to check each bit of the command-line and it was working fine.
To show case how painful it was, he showed me one of its application implementing his new function, but he forgot the supported command-line parameter.
Note: Solution with cool effects shared in comment.