In Joseph Heller's "Catch-22", the character Colonel Korn reflects on the idea that one negative influence can have a detrimental effect on a group, expressing this irony with the metaphor of a bad apple spoiling the bunch. This observation encapsulates a broader commentary on how individual actions or attitudes can impact collective well-being.

The phrase suggests that even in environments where many are well-intended, one person's negativity or poor decisions can undermine the integrity and morale of the whole. Heller uses this irony to explore themes of absurdity and the complexity of human interactions amidst the chaos of war.