Yeah, this one's actually true. Avoiding extreme contact heat to his manhood will keep your guy's sperm count nice and high. Sperm is best produced when the scrotum is about one degree cooler than the rest of the body. Think for a second about the difference between male and female bodies — ovaries are housed inside a woman's body, where they're protected and kept warm. Testicles are outside a man's body, though, which shows us that their natural preference is to be cooler. If he simply can't resist a steamy soak, keeping the temperature below 99 degrees should keep his sperm safe and sound.