OC: @Austin Sims The 20-foot measurement comes from the epididymis, which is a tightly coiled microscopic tube attached to the back of each testicle.If you were to completely uncoil and stretch out just one of these tubes, it would measure about 20 feet long. Here is how the journey inside the body breaks down:Maturation and Storage (20 feet): Sperm is produced in the testes and then travels into the epididymis, where it spends roughly 2 to 4 weeks maturing and gaining the ability to swim. The Launch (1.5 feet): During ejaculation, the sperm is propelled out of the epididymis and into the vas deferens. The vas deferens is a muscular tube measuring about 12 to 18 inches long. The Exit: From there, the sperm passes through the ejaculatory ducts, mixes with fluids from the prostate and seminal vesicles to become semen, and is expelled from the body via the urethra.