make (one's) bones(redirected from make their bones)
make (one's) bones
1. To kill someone in order to obtain membership in a criminal organization. Used in this way, the phrase is often associated with the Mafia. A: "Has Johnny Dukes made his bones yet?" B: "Not yet, he's still a low level guy."
2. To solidify one's reputation. He made his bones as a big city detective before joining our town's police force.