Johnny Test (2005)

S5E23 Johnny Two-Face

Frustrated by Johnny's endless deceit, Susan and Mary decide to take matters into their own hands. They attach a second mouth to him, one that is compelled to speak only the truth. As Johnny struggles to balance his two conflicting voices, chaos ensues, leading to unexpected revelations and challenges in his relationships. The experience forces him to confront the consequences of his dishonesty and re-evaluate the importance of integrity in his life.