When your balls and scrotum are ravaged, sore and swollen from being pleasurably whipped with a riding crop during a spirited session of derby balls.
My sack is so sore. I have crop balls.
My mistress gave me crop balls and it hurts so good.
Doctor: I’m a little concerned about your scrotum. How long has it been this swollen and enlarged? We need to do some tests.
Patient: No need doc. It’s just crop balls. They were whipped good last night.
Doctor: This is my third case of Derby Balls this week. I should have known.