What happens to the testicles when they're exposed to the cold?

Retract upward. Exposure to cold will normally cause the testicles to retract upward (creamsteric muscles). This is to help protect the testicles and testicular cells from cold temperatures since sperm are very sensitive to temperature changes, even as little as liitle as a 1 degree change. This may affect the quality of sperm if chronically exposed low or high temperatures, especially heat.