The egg shaped sex organ held in the scrotum, leather sac under the male's penis.
The primary gland, contained within the scrotum, that produces male sperm and male sex hormones. Testosterone being the most well known, but not the only sex hormone.
Having Balls is also a euphemism meaning that one has extreme guts, or courage in the face of danger or adverse conditions.
Balls of Steel is a term meaning a person has great nerve, that they are able to face extremes without showing signs of the associated stress.
Blue Balls is a slang term, which is about a fluid congestion (temporary) due to excessive (prolonged) sexual arousal of the prostrate and testes.
The SRY Gene usually located on the Y Chromosome determines the presence of testes, and its lack allows for the gonads to become ovaries. This is during the gestation period of pregnancy.
Internal reproductive organs then determine the process into forming the penis, and scrotum, or lack of them, based on the hormones created by the ovaries or testes previously formed, and the reaction of the cells to them. The presence of testosterone helps develop the penis and scrotum.
Male testes generally have one that hangs lower than the other, due to differences in the left / right anatomy make up. Studies claim that 85% of most men have their left testicle hanging lower than the right.
Size is considered to be between 14 cm3 on the low end, and 35 cm3 on the high end.
History (Legend): The rising up of the testicles is not about being close to ejaculation, but about insuring that proper 'core temperature' is maintained, and there are reports that say that prior to ejaculation, the scrotum actually lowers the testes, showing a sign of complete relaxation, allowing for the orgasm to occur. Balls being lifted up is a natural body reflex action meant to protect the fragile balls, and occurs in a heightened state of stress.
Most common practice is to suck on the leather sac, taking the hard egg shaped testes into the mouth, and licking at them. Some simply poke and prod, suck briefly, as if to stimulate the sperm production.
This generally is standard practice during oral sex rituals.
Some will pull the sac, and bunch it up in order to try and contain the moment of ejaculation, though no evidence exists it has any actual effect.
Practice (Associated Acts): The taking of Steroids, and other similar type drugs can decrease the size of one's testes, as well as harm its production of sperm, release or production of testosterone hormones. In short, it can effect one's sex drive or ability to reproduce.
Noteworthy: Size and capacity to produce sperm appears to be larger or greater, in those with multiple sexual partners, such as those in polygamous relations versus monogamous ones.
Temperature does play a role in the release of sperm from the testes. The closer to 'core temperature' is ideal for the production of sperm, while the hotter the temperature the less efficient is the production of sperm.
Substantially cooler temperatures also effect the production of sperm, and is a possible explanation of why a male's scrotum shrinks when exposed to cold temperatures, below the body's 'core' temperature.
The shrinking is the bodies mechanism, to try and maintain the core temperature of the testes.