This study explored how social media users' mocking of a public health campaign can affect other users' emotions, cognitions, and behavioral intentions. Inspired by public mocking of the CDC's "Say No to Raw Dough" campaign aiming to prevent food poisoning caused by eating raw flour-based products, this experiment (N = 681) employed a 2 (Public responses to a PSA: Mocking or serious) x 3 (Organizational response to public responses: Self-mocking, serious, or none) + 1 (control condition) design. Statistical tests revealed that user-generated mocking can lower intentions to avoid the health risk by decreasing perceptions of injunctive norms (that is, seeing others mock a public health campaign resulted in weaker perceptions that others think you should avoid the risky behavior). Mockery of a public health campaign also engender anger at the CDC and at other users, with the target of the anger having differential effects on intentions to avoid eating raw dough. Implications for theory and the practice of social media-based health promotion are discussed.