A 48-year-old woman with gradually growing left lung nodule underwent FDG PET/CT scan, which demonstrated mild F-FDG uptake in the nodule of the left lobe, suggestive of malignancy. Unexpectedly, increased FDG uptake in bilateral gluteus medius, gluteus minimus, and piriformis was shown. She described having sexual activity in missionary position the night prior. The case emphasizes the importance of avoiding sexual activity before the FDG PET/CT study.