Typically a metal cotter pin like device for keeping a land mine or hand grenade from going off, however in this case it is
used as a synonym for a companion who keeps you calm or from getting upset or "exploding with anger or lashing out'.
"Please stay with me you can be my safetypin.."
(used in Korean movie 'its ok not to be ok)
where military service is required by all and understand how these war devices work
mostly a metal device used for holding together wedding dresses and clothes....but know has been exploited as a fashion to those who are interested....but if not I bow to you who want to hold your clothes on