Hydrocele is a very common condition that is simple to evaluate and treat. Management of hydrocele is usually delegated to the junior members of the surgical team. Sometimes this simple condition can spring huge surprises. A 20-year-old man presented with acute onset large, painless fluctuant left hemi-scrotal swelling. Scrotal ultrasonography showed thickened tunica vaginalis. A diagnosis of left hydrocele was made and repair by excision of sac was planned. During the procedure, the sac was found studded with red nodular growths; histopathology reported malignant mesothelioma of tunica vaginalis. Metastatic evaluation showed extensive retroperitoneal lymph nodal involvement. Despite receiving adjuvant chemotherapy with radiotherapy patient died due to extensive metastasis within 16 months. This case is presented for rarity of diagnosis, young age of presentation, absence of etiological factor and rapidly progressive clinical course.