I know the engineer who set this up, I reckon

My internet connection is slow and transmission stopped for a minute with the complete sign visible, except for the unexpected last line. It was well worth the wait!

Looks more like being set up by a lawyer.

All that sign needs are a few bullet holes.

It's missing one thing; a sticker advertising the services of a surgeon who specializes in reattaching fingers.

Self-referential humor usually works well. Strange loops.

Is this thing real? Where is it?

It's not real. No traffic engineer would care a whit about people cutting their fingers on a sign.

Probably no one here is old enough to recall the Australian cartoonist Emile Mercier, a favourite of my father.

Mercier used to do things like that in his cartoons.

I recall a scene of a golf course - off to one side was a sign saying (only) "Do not lean golf clubs against this notice".