In some male mammals the scrotum is a protuberance of skin an muscle containing the testicles. It is an extension of the abdomen, and is located between the penis and anus. In humans and some other mammals, the base of the scrotum becomes covered with pubic hair at puberty. In common speech, the scrotum is often improperly referred to as the testicles, which actually refer to organs encased inside the scrotum. The scrotum is homologous to the labia majora in females. It becomes tight when sexually aroused.