No Alcohol Beyond This Point
Ever seen a sign like this ? I've always wondered what such a sign could possibly mean. A point is the intersection of two lines. It occupies no space and doesn't even occupy a dimension. It literally doesn't exist; it's more of a concept. There's certainly no way to represent a point on a sign, and usually the sign people make no effort anyway. So the point in question could be anywhere in the universe. They could maybe indicate which particular point they meant with a mathematical formula but then they'd have to paint hatch marks all over the walls so someone could attempt to find the point referred to. And when you did find the point, what then? Is there any way to be beyond a point? I think you're always this side of a point (unless the point is inside you, but let's leave that out for the moment). Perhaps they mean line, as in "No alcohol beyond this line" and then they could have a segment of the line in question to indicate what they mean. But you run into much the same issue; there really is no way to be beyond a line. Wherever you go if you observe the line it is before you, unless you go to infinity to either end of the line in which case you could observe it as a point, but then you run into the problems with points as mentioned above. At least the sign didn't say "The line for alcohol starts here" because then that would make "here" infinity and there would be all sorts of difficulties with existence.
It could be the sign makers meant to say "No alcohol beyond this plane" and the sign itself could be a small segment of said plane, although infinitely thicker and infinitely smaller than the plane it was trying to represent. You get the same sort of issue about being "beyond" the plane but you could get around this to some degree by printing "No alcohol beyond this plane" on both sides of the sign, and then leave the actual meaning up to philosophers.
Or the intent might not be the plane but an area contained within it, as in "no alcohol beyond this area". Of course, an area is kind of a self-contained thing. In a curved universe there is literally nothing beyond an area. If you attempt to leave the area on its right side you will simply re-enter it from the left. So maybe the intent is more "no alcohol in this area" and they could have an army of two dimensional guards protecting the borders of the area from the looming threat of alcoholic aliens from the third dimension. But these clever aliens could simply jump into the area, drinking with impunity, and when the guards arrived they could jump out again, simply vanishing into a higher dimension and leaving the guards with a baffling story to tell their flat children.
On the other hand, if the sign were shaped like a platonic solid and said something like "No alcohol beyond this dodecahedron" then you'd be getting somewhere. All space outside of a regular solid is in fact beyond the solid, while all space inside it is within . So such a sign would be inviting people to crawl inside and have a drink. Although there's really no good way of getting comfortable inside a dodecahedron unless it is a particularly large dodecahedron.
Or possibly it's all a semantics thing, and it's really a warning that alcohol ceases to be available in some kind of proximity to the sign in question. In that case a prudent person would order another round and drink up, likely away from the annoying and confusing sign. Maybe there's a nice place outside somewhere, beyond that sign maybe.