A 26-year-old male who endorses daily cigarette smoking and marijuana vaping presented to the emergency department with acute onset of left-sided chest pain radiating to the left shoulder. Physical examination was unremarkable, but laboratory investigations showed elevated white blood cells, cardiac biomarkers including troponin and creatine kinase, and mildly elevated C-reactive protein levels and erythrocyte sedimentation rate. Electrocardiogram displayed subtle ST-segment elevation in a diffuse pattern, leading to a diagnosis of acute myopericarditis. The patient was treated with anti-inflammatory medication and supportive care and instructed to cease cannabis use.