Penis and Testicular Health Introduction: The penis is the external male sex organ. When erect, the penis can be used for masturbation, vaginal, oral, and/or anal intercourse, and a wide range of other sexual behaviors. The testicles (or testes) are the male reproductive organs. Testicles are oval-shaped and housed in the scrotum, a sac that is found just beneath the base of the penis. The testicles are where sperm are produced, and it is normal for one to hang slightly lower than the other. Testicular cancer is a very real health concern for men starting in their twenties and thirties, so they should do monthly testicular self exams to feel for any abnormal growths in their testes.