You can just hide one of these in a fold of fat (unless you are one of those skinny types!). Or just put it under a bandage. I think you can wear a bandage at a nudist camp. Not sure, never been to one.
I saw a write up about the 2mm in a cartridges of the world book some years back and, to paraphrase: This cartridge could never be considered adequate for hunting or defense, although it may do to dispatch a trapped mouse or an overly aggressive cockroach.