LPT: Check for (&remove) random out of place objects (usually trash) outside your house: it may be a sign used by burglars/thieves.
I'm not sure if this was posted before, but thought it might help anyway since these type of signs/markings change over time, and also place. Sorry if I also used the wrong flair, first time posting..
I'm from South Africa and I'll be posting some things that our police has indicated, especially in the norther parts of the country, but please feel free to post anything you know of from your community/country.
• Z painted on a stop sign or on the road means that all the houses in the street are marked.
• Piles of small stones are an indication of dogs and two big stones together means there are old people living in the house.
• Red objects mean resistance, for example, two red tins means that the owner of the house is armed. Red soft drink can with the opening towards the house – someone is home.
• Upright soft drink can – nobody home.
• White objects (or plastic bag) mean the house is an easy target.
• Green objects are used as direction markers.
• Blue objects mean the house is an easy target and there will be help from inside.
• Two big stones together – two old people.
• Stones placed in a row – indicates how many people in the house.
• Swastika painted on road – houses in street targeted for burglary. Direction of swastika indicates which house is the target. (these days it might be something completely differently, but I guess it depends on where you're from, I don't see this in Cape Town ever)
Anyway, it is probably a good idea to pick up trash regardless of why it is there, so this LPT tl,dr can just be "pick up trash please" . Stay safe everyone