Vaginal rupture leading to pneumoperitoneum is well documented to occur after hysterectomy or surgery. However, it is extremely rare in a young woman following conventional intercourse. We report one such case. A 16-year-old woman presented to the accident and emergency department with a clinical picture of an acute abdomen. Results of radiography showed gas under the diaphragm, suggesting the possibility of bowel perforation. A detailed sexual history pointed toward the possibility of vaginal trauma. Diagnosis was confirmed on examination under anesthesia, and the tear repaired. A concomitant laparoscopy ruled out any other intra-abdominal injury. This case reminds us that acute peritoneum can occur after sexual intercourse and also reiterates the importance of a detailed sexual history and vaginal examination in young women presenting with an acute abdomen.