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@freemo

The thing that caused me to wonder now was a shaving cream can, where I could test the pressure inside by deforming it with my fingers first.

I also saw such a warning on camping gas bottles (some mixture of propane and butane), which did have a way of ensuring they're empty provided: there's a plastic shim you can push into the valve to permanently open it (so that you can vent the bottle after you used up the gas). In such cases I don't really see a reason not to amend it to say "don't puncture unless the shim has been inserted for a few minutes".