In the air wing, we actualy weren't allowed to wear them on the flight line/deck because they posed a FOD hazard.
On the carrier, s.o.p was to lace one into your boots. The theory being, that if you got inhaled by an A-7, etc., they could at least identify the pieces.
I never wore mine in civvies, nor did any of my squadron mates. The young, gung-ho grunts never took theirs off.
Once received a beasting for calling them the above. "No you ******* numpty we're not Yanks, (no offence BNY) and they are called I.D discs" Other pearls of wisdom included calling a GPMG a "Gimpy" and one lad called a D.L Sarge!! Oh dear did we get a collective beasting!!!!!!! Mind you his unofficial nickname was nookie bear and yes his was the spitting image equiped with the said right hand up his jaxy!!!! weyhey!!!!!!