Testicles, balls, nuts, goolies, there are many ways to describe the penis' two loyal sidekicks. But how much do you actually know about them?
Sure, we know they produce spermatozoa and hormones. But did you know they can up to double in size during sex? Or that squeezing testicles too tight can release a deadly amount of adrenaline?
Thought not. Watch the video above for seven facts about testicles that will make you feel weird.