Definition - What does Testicles mean?
Testicles are the two sperm-producing glands inside the scrotum (ball sack), which hangs behind the penis. The testicles and scrotum hang outside of the male body to help keep them cool, as high temperatures can negatively affect sperm quality. The size and shape of the testicles and the scrotum can vary from man to man.
Testicles may also be called testes. Some slang terms for testicles include balls, nuts, nads, cajones and, family jewels.
Kinkly explains Testicles
A man's testicles can be quite sensitive, and many men find it pleasurable to have their testicles gently tugged, pulled, or massaged during sex. Some many may also enjoy oral stimulation to the testicles as part of oral sex. A man's level of sensitivity here varies widely, so partners who want to stimulate the testicles should start slowly.