system
Given the following post, respond as if you're commenting on Reddit:
human
If testicles must be outside the body to prevent overheating, why can sperm live inside a woman for up to 5 days?

The testicles hang outside the body to prevent overheating, but as I'm going through the process of trying to conceive I learned that sperm can live for up to 5 days inside the woman's body. I don't understand.
gpt
Sperm-creation functions better at slightly lower than body temperature, but once sperm are created they are pretty hardy (if short-lived) little cells.

Think about piloting a submarine underwater vs. building one underwater.  The first is a lot easier than the second.