When incomplete strangers - i.e. not literal complete strangers off the street, but people who've been introduced to me by a mutual friend without having any idea who I am - ask about my cryonics necklace, I often lead with, "It's my contract of immortality with the Cult of the Severed Head".

This seems to work fine.

In fact, I strongly suspect it works better than most other cryonics explainers, because I don't sound the tiniest bit nervous. It helps to understand that most people have no independent grasp on reality. I may post about this at some point.

In any case, this is successful countersignalling performed on very loose acquaintances.