[floatrock]

That's a real phenomenon -- they're typically called Trap Streets https://en.wikipedia.org/wiki/Trap_street https://www.atlasobscura.com/articles/trap-streets-with-no-n... -- but that's a bit different from these easter eggs.

You put a drawing of a marmot in a mountainside or turn a stream into a naked lady to have a chuckle and get one over your boss, not to enforce copyright :)