Goodfellaoggie is right. It's like a license for underworld wiseguys. To get this license you have to "make your bones" like lil mafia said. It usually means, kill someone although some made members have been known to be initiated without having killed someone. Say they could be a very good earner, hijacker etc.

Now with this license made members within a Mafia Family would look upon outsiders as just civilians or if they work with them, like Pesci's character they are associates. Pesci as Tommy in Goodfellas made a fatal mistake in whacking Billy Batts. It eventually led to his death.

ScarfaceRH, if you havn't already, check out the film Donnie Brasco, not only is it an awesome Mafia film but it really gives insight into the rules and basics of the mafia. Plus the star cast is worth seeing alone anyway. Pacino, Depp, Madson....