Another saying I liked in that same vein is: "An engineer is an unordinary person who can do for one dollar what any ordinary person can do for two dollars."
There are other examples of this. Some are entirely deliberate. The ISO-9660 volume structure was deliberately designed to allow it to coexist with other file systems present on the same disk, for instance.
I remember something like this from one of my security classes..
Its a shellcode which works on 2 platforms... its designed so that the executable code on 1 platform is interpereted as NOPs or other harmless commands on the other platform and vice versa
I remember getting a game demo back in the early '90s on a 3.5" disk that would work on both DOS and another platform - I think Amiga. It didn't last long when I tried to copy a file to it, unfortunately!