That’s one of their rules. Now that’s not going to get you killed obviously, [but they] want you to be neat at all times. […] So you need to be clean shaven, keep your hair trimmed and in evenings you’ve got to wear slacks and a sport coat. You don’t have to wear a shirt and tie, but at least wear slacks and a sport coat. [They] want you to be presentable at all times.
Joseph D. Pistone (aka Donnie Brasco) testifying on how the Italian Mafia told him to dress. (source: Quebec’s Charbonneau Commission)