It is an analogy, please seek medical advice if you have real pain or soreness in your ball bags, as you may have an STD.
That would be a double ball ache.
There is only one cure to ball ache, and that my friends is known as a wank.
B: Ball ache.
A: I thought you were with Jane last night?
B: Indeed. She may look like a pro, but sadly she couldn't finish off a packet of crisps.
A: Sorry to hear that
B: Shhh... I'm off to wank.
Melinda: Well, my brother was in the room next to me just whacking off all day, this morning he was walking weird cause he had such painful ball ache.