Hmm. Edible RFID chips, perhaps? Some type of gummy-chip that solidifies/self-heals and activates in digestive fluids...
Someone is conducting a trial to see how noticeable they are, and how long they will function, by slipping them into Grrrl Scout cookies. However, their monitoring stations are on the low end of data security, and the ping packets have been co-opted by other advertising systems. The net result of which is that anyone who has swallowed one will be beseiged by AR and trid ads in any commercial/retail environment (a bit of extra Noise, and perhaps a Sneaking penalty). A bug sniffer can detect them, but treat them as Stealth RFIDs for that purpose.
How long will they last? Who knows?
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