It's all about content, isn't it?
It's all about the story, the message, contained within a photo.
This is my favourite warning sign. Not the No Trespassing one, or the surveillance one: the other one. I've never seen another like it anywhere in the city, and I suspect that it's custom made. I actually suspect that it's something of a joke as well, because even though there was a drain outflow beneath it, I doubt anyone is actually discharging waste water into a back alley in downtown Toronto.
On a commercial scale, anyway.
Or at least, if they are, they probably don't advertise the fact.
The sign itself is interesting. The title, "Warning", is in Helvetica. The body text, "waste water discharge can occur at any time", is in Arial. These fonts are similar enough to confuse people who are just looking to match one to the other on their PC, but a designer wouldn't make that mistake, and certainly shouldn't mix the two.
A professional sign maker probably also wouldn't write "anytime" as one word.
But the sign is very neatly installed, and was probably done at the same time, or at least by the same person, as the "No Trespassing" sign next to it. (That sign looks like it's in Impact, a favourite of sign makers and meme generators alike.) So it probably wasn't just put up as a lark, no matter how odd or improbable its origins are.
And no, I didn't linger in the area to find out if its warning was true.