The [testicles] or [ovaries] -- in either case, the pair of organs which:
a. Produce hormones which, prior to birth, cause the development of gender-specific traits, and at puberty, cause the development of secondary sex traits. [Testosterone] for males, [Estrogen] and [progesterone] for females.
b. Produce gametes (sex cells) -- [sperm] in the case of males, [eggs] in the case of females.
c. Make young boys giggle.
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