In 1982-3 I was assigned to 80 TFS, Kunsan in the Life Support shop. The Juvat tradition is that Tac Call Signs are assigned upon Green Bean tours and are permanently engraved upon your challenge coin.
The rule seemed to be that your call sign would be something that you would object to. My last name is Scism, so The LSO was tasked with designating my call sign, but he was over-riden by the DO, who decided my call sign would be Circum-Scism.
The policy of course was for identification purposes if war broke out. and if we called in, by phone or radio this would be part of authentification. So in the bar, in Silvertown, when I drank my Juvat Cocktail and was ceremoniously dubbed, The squadron declared that if my my Tac Call Sign was to be Circum, I had to demonstrate that I was Circumcised.
Audentes Fortuna Juvat!