If you're worried about break-ins at home, this could help . . . A former burglar claims the best way to prevent them is also one of the cheapest: Just put up a sign that says "BEWARE OF DOG".
If you have a dog, great. But it works even if you don't. He says the average burglar won't risk it. They'd rather move on and try another house instead.
He says it's more of a deterrent than those signs that say you've got a security system installed. And they only cost about five bucks on Amazon.
There might be a few drawbacks though. For example, they're not exactly nice to look at. So your neighbors might not like it.
Also, someone on a Reddit thread said they put one up at their new place. Then friends kept calling from outside the first time they came to visit. They knew he didn't have a dog, and thought they had the wrong address.