Deterrent Win

found on Reddit

Apparently this was the result of a tree rather than a dog, but would-be trespassers don't need to know that.

When Harry Met Fido

found on Dump A Day

Are you not deterred? I know I am.

Pistol Pooch is on patrol

from here and here (image source)

I'm not sure how hes' supposed to draw that gun out of it's holster(?) and I wouldn't want to stick around to find out. 

Beware Of Dog 2.0

found on EvilMilk

I'm not sure if this is more or less effective than standard beware of dog signs when it comes to deterrence. Can you tell what kind of dog it is? Not exactly. Can you tell how big it is? Again, not exactly. It doesn't appear to be one of the very tiny breeds, but there's still an element of the unknown here which is important in fostering fear. I guess what this one does is evade the parts of our brains that have grown to ignore beware of dog signs.

Beware of tacti-camel

from here and here (image source)

I think it may be time to update our threat models about camels. Some of them may be capable of more than we anticipated (even if it's only inadvertently when the gun gets knocked around).

If you can read this it's already too late for you

found on Dump A Day

There are a number of ways to boost the deterrence capability of a warning sign. This one adds uncertainty about whether it might already be too late to turn back, prompting people to make a quicker, less thought out decision to leave.
 

You've got to get up pretty early to get past him

found on Reddit

Under the right circumstances these animals can in fact be quite vicious. If someone put up this sign there's a good chance that you should  be at least as cautious as if there were a beware of dog sign.

Taking a bite out of crime

found on Imgur 

Based on the actual story it seems likely that the blood was a result of shall we say self-inflicted wounds as the burglar tried to escape through the window they broke on the way in - though I'm sure the dog named Demon helped make that escape more difficult and injury prone.

Aaaaaaaaaaaaaaah-dorable

found on Funny Junk

At least this one actually attacks, and those little teeth are sharper than big ones so look out.

Expectation vs. Reality

found on Animals Being Cute

The sign might keep people away, but the actual dog would have the opposite effect. Hide that dog.

Are you feeling lucky?

found on The Art Of Trolling

I don't know about you but I wouldn't want to play guard dog roulette.

If he's not afraid, I'm not afraid

found on Dump A Day

A sign can be a perfectly good deterrent all by itself, as long as nothing contradicts it.