It could probably be setup to be just a brief toot during the initial lift, then not go off again until the next lift. Perhaps with a delay between toots to help minimize abuse.
I was imagining it was in the men’s restroom for some reason while reading that and the story seemed weirder in a gun shop of all places, but I guess it makes more sense in the women’s restroom. I wonder if they had installed a similar picture of a naked woman in the men’s restroom.