Blue balls
Blue balls is slang for an uncomfortable testicular sensation that can occur during a state of male sexual arousal. The term is thought to have originated in the United States, first appearing in 1916. Another slang term used for the condition is lover's nuts. Some urologists call this condition epididymal hypertension or sexual arousal orchialgia. Most often it describes a temporary fluid congestion (vasocongestion) in the testicles, caused by prolonged sexual arousal in the human male without ejaculation. Research. The phenomenon is sometimes associated with certain demographics, such as men who are experiencing and practicing delayed, multiple  or inhibited ejaculation. Since the pain level is usually low, it does not affect sexual activity—thus, is rarely considered to be pathological. This leads to a wide discussion, with scant information in the scientific literature. A brief article by Chalett and Nerenberg in "Pediatrics" agrees that little formal data exists regarding the condition. The article concludes that "the treatment is sexual release, or perhaps straining to move a very heavy object—in essence doing a Valsalva maneuver." Causes. The cause of blue balls is a large amount of blood circulation to the genital area, specifically the penis and testicles , without the release of tension associated with orgasm/ejaculation. When a large amount of blood flows to the genital region, the penis becomes erect and the testicles also experience increased blood flow and swelling. Other causes of painful symptoms include: It may also be a sign of testicular torsion, which often requires emergency surgery. Symptoms. The following indications and symptoms in the testicles may be experienced by people with blue balls: