gang of hoodlums; bad company; delinquent friend
Refers to a group of juvenile delinquents or a friend who is a bad influence. Often used in contexts of youth crime or peer pressure.
He hangs out with a gang of hoodlums and stays out late at night.
I was led astray by bad company and ended up shoplifting.
Compound of 不良 (delinquent, bad) and 仲間 (companion, group). The exact historical derivation is uncertain, but the combination straightforwardly means 'delinquent companion/group'.