I think one of the most bizarre museum practices is the act of marking museum artefacts with an accession number. Like the tattoos of gang members, it is a permanent symbol which marks their lifelong membership in a collective from which they can never again be completely separate.
The most common tattoo among gangsters of all nationalities is one that denotes the gang that they are in. This is seen as the mark of lifelong membership. The gang ethos of “blood in, blood out”–the idea that the prospective member must kill someone as the price of admission to the gang and cannot leave except by dying himself–is embodied in the tattoo as a sign of permanent belonging to the gang.