F-FDG is the most widely used PET tracer worldwide. Before the examination, recommendations are given to patients to avoid muscular activities, with the goal to limit F-FDG uptake in muscles. Here, we report the case of a 36-year-old man with Hodgkin disease referred to our department to perform an F-FDG PET/CT for immunotherapy assessment. The PET images showed a homogeneous, symmetric, and very intense uptake of the masticatory muscles. The medical examination exhibited a trismus, and the patient revealed to have been using cocaine 15 minutes before injection of F-FDG.