I don't think that anyone outside of the Mob even knew what "making" a guy meant back when the movie came out.
Joe Valachi revealed the Mafia induction ceremony during his testimony before the US Senate in 1963.
I agree that back then there was some public knowledge as far as Mob ritual.I meant to say that when the movie came out,the average person on the street wouldn't be as familiar with the term as they are now. Back then you wouldn't hear a bunch of guys in a bar after their softball game talking about "made guys" and "gettin' whacked". However,the phrase "sleeps with the fishes" might have slipped in.