You probably mean this: https://en.wikipedia.org/wiki/Trap_street

Speaking from experience, it's more often bored cartographers trying to inject some fun into mundane activities.

I used to try and write my initials.

Quite often it devolves into a game of seeing what you can get past the reviewers

Interesting perspective. As an OSM contributor, I've never had this thought. You presumably spend up to 8 hours a day mapping, all week long (depending on the week perhaps), which I can totally imagine gets old. I only map when I feel like it and not when I'm bored

And on OSM we don't have boss fights in the shape of reviewers. That does sound like a fun challenge :P

I would think that they are too recognizable for that. It would be better to subtly change one insignificant squiggle into another.

They're only too recognizable if the someone's paying very close attention.

Vs. if they're not, and Swisstopo can point that out - the internet can enjoy pillizing the perp.