Love it! I've seen a lot of signs like, "prohibited items are not allowed in facility." Especially TSA signs at the airport which also include guns and knives and such in big red circles with lines through them. I always wonder if those signs were made by a brilliant low-grade troll or not.

I once added text that said, "Unauthorized access is not authorized" as a low-grade troll, and people liked it so it stayed

You can think of “Prohibited items” as a variable which happens to be called like that for clarity. It’s a clearly defined arbitrary list and it’s referred as such in any relevant text. The prohibition starts at an arbitrary point in the building so they reference the variable when communicating this to you.

No Spitting. The Mgt.

"The Midget."

Similar feeling with "No trespassing"... like, duh!