On a related note, those little detection stickers
make great practical jokes
I was goofing around with one of the stickers at home, and I set it on the table. My wife came along and set her purse on top of it. I forgot about the sticker until later that night, and when I went to get it I figured it had been tossed or one of my kids had it. The next day my wife went to the store, and her purse set off the alarm. They suspected she had stolen something, and after a few passes through the detector, they narrowed it to her purse. They dumped it out on the counter, and when everything had fallen out, they noticed the sticker on the now upside-down purse.
My wife was very embarrassed, and they refunded her money. So, inadvertanty, they gave her $60 worth of stuff for the inconvenience.
I never did tell her where the sticker came from. I just nodded a lot as she angrily recounted the story.