READ MORE: Average UK penis size revealed – and it ranks 66 on the global scale Inside the scrotum, they sit at a temperature of 35 degrees celsius, prime real estate for manufacturing sperm and testosterone.The cremaster muscle, which is responsible for movement, expands and contracts, according to temperature, says WebMD.And when the temperature is too hot, the balls hang long, when they're cold, they come up as close to the body as possible.One Reddit user pointed out the fact, as they asked: "Always visibly moving.
Who's watching them?"Another replied: "My wife. She gets a kick out of it. I never knew this was a thing until she pointed it out."A third added: "I also noticed this on my hubby while lazing about on the couch one day.
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