Back on Wing Commander 1 we were getting an exception from our EMM386 memory manager when we exited the game. We'd clear the screen and a single line would print out, something like "EMM386 Memory manager error. Blah blah blah." We had to ship ASAP. So I hex edited the error in the memory manager itself to read "Thank you for playing Wing Commander."
(This will be understood only by those who lost countless hours tweaking their autoexec.bat and config.sys to squeeze that last KB of memory needed to run the game they were supposed to spend the weekend playing ).