bad apple—(coll.) a single bad person in a group (also: rotten apple):
- Maybe she was the bad apple of the department, so I made an appointment to meet with another woman.
bad egg—(coll.) a bad or despised individual (also: rotten egg ):
- Billy was a bad egg and spent most of his time trying to deceive the villagers.
Cf.: good egg—(coll.) a proper and decent person:
- Despite what most people around here think, I think George is a good egg.