[NSFW] I've heard medicine balls are great. How do I get the medicine in mine?

What medicines work best in balls? Are there medicines women particularly prefer more than men, or are they pretty much unisex? And are there any medicines that cause more grief than good in your balls? I’m not sure how to get the medicine in the balls, but it strikes me that the wrong method might hurt or even damage my balls. What’s the safest, most painless method to administer medicine to the balls?