I believe this was censored on reddit. This post isn't a pro-murder post. Mostly wondering how they put this sign up safely.
I always wonder the same about people's tags that are in places where you'd need to be Spider-Man to reach safely. How did you get there, then stay for long enough to put up your message, without anyone noticing or saying something?
I'm half convinced these things just show up on their own. It's magic.