As I was reading Sam's recent post on the Proto-Sinaitic language, I was reminded of a group of people that used symbols in the modern day that meant specific words to inform others of what lay ahead. Who am I talking about? The hobos of the Great Depression! I remember reading about the hobo symbols in my American history class a few years back and thought it was hugely interesting. So, my comment is now turned into a short post.
The hobos used symbols such as the ones below to help them know where they could find help and food during their hard times. Not only this, but they could also communicate things such as dangerous drinking water or that a town was not good for strangers because there had been a crime. A better list of symbols can be found here. Click it, it's fun! I just always thought it would be funny for someone to walk outside of their house and find a sign that meant they were ill-tempered or a sucker.