Do penises and or testes shrink if men abstain from sex for several years?

No, there is no scientific evidence to suggest that penises or testes shrink if men abstain from sex for several years. The size of a man's penis and testes is determined by genetics, hormones, and age. While sexual activity can affect the appearance of the penis, such as causing it to become erect, it does not have any long-term effects on its size.