"No Firearms", with a drawing of a pistol and the standard red circle with a red line across it. This sign was part of a neat three-by-two array of other signs (no smoking, no pets, etc.) at the entry to a mall in the small city of Nelspruit.
These signs (without the symbol) are actually reasonably common, as are drop-off points for firearms on entry into various private areas. I don't have one with me so I don't know what the procedure is. Presumably it's like any other claim check arrangement.
I'm wondering if places like Texas have this. I don't think I've ever seen a firearms drop-off point in the States, although the standard Vermont boilerplate sign outside courthouses saying you can't bring in firearms implies that there must be something you can do with them. Then again, it being Vermont, you can probably just leave them in your unlocked car. (Okay, I exaggerate slightly, but not much.)