What’s the backstory behind this sign? IIRC, this image must be at least 10-15 years old. Is it real?
Can you link the sign itself instead of linking a google search from not-America?
Just google “this sign has sharp edges”.
The story behind it is: Photoshop.
It’s obviously a parody of (real) signs that used to be fairly common. It used to be (and this ain’t ancient history - I’m in my 30s) that if you bought knives, you would see the “severed fingers” image on something in or on the box. I’m sure that image is still out there. But making a sign to say that the sign has sharp edges is pure satire.
My favorite (first saw one of these in Mad Magazine decades ago).
Here’s a picture of the sign. If you read it in its entirety, it’s not just self-referential. After the conspicuous warning about the sign itself, there’s a warning in fine print at the bottom that the bridge up ahead is out.
Why does everyone always jump to the conclusion of Photoshop for things like this? It’s just as simple to assume that someone made up a bunch of sharp edges signs, for the obvious reason, and that some other folks bought them and put them up, again for the obvious reason.
I have been having fun with this ALL DAY !!! 
Can’t tell if serious
I agree with Chronos. There is vastly more humour in actually making the sign. More to the point I have made joke signs. Sometimes they cost real (as opposed to not much) money, but it can be well worth the expense and effort.
Just photoshopping up a fake picture of a sign, and posting on the web is, at best, a trifle lame. Especially compared to actually making up a sign and placing it somewhere appropriate.
Lame it may be, but I suspect photoshopped signs are significantly more common than real-world fake signs - therefore ‘photoshop’ isn’t an entirely unreasonable assumption.
Reminds me of the B. Kliban cartoon that has a huge sign in a bus statio n reading:
In our garage, in front of where my car goes, is a very real looking sign. Kayker parking only, then it explains about violators being towed, gives the specific vehicle code law in finer print. It was a gift from someone.
As I pointed out in a thread several months back, there is a sign on the side of a building less than a block from where I’m sitting that reads: “No parking. The insane parking monkey takes no prisoners.”
Me too!
The production manager is gonna be PISSED.
Caution : Safety Glasses are meant to protect your EYES, NOT your forehead !