You might be thinking of the scrotum, which is a pouch of skin that hangs behind the penis and contains the testicles.

Here's what the scrotum does:

* Protects the testicles: The scrotum acts as a protective barrier for the testicles, keeping them safe from injury and impact.

* Regulates temperature: The scrotum helps regulate the temperature of the testicles, which is crucial for sperm production. The scrotum can contract and relax to adjust the distance of the testicles from the body, keeping them at the optimal temperature.

* Supports the testicles: The scrotum provides support and structure for the testicles, ensuring they are properly positioned.

Let me know if you had something else in mind!