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.