The Horse or the Jockey?

I'm catching up and watching the Rushaway Stakes on the DVR this evening with my 9-year-old son. After the win by Cliffy's Future, they went to Jeannine Edwards with the news that the colt was scheduled to be gelded after the race.

My son was intrigued by the word and thus asked for its definition. The conversation went like this:

Son: What does that mean?
Me: Do you really want to know?
Son: Well, yeah, I do.
Me: It means that the Doctor will cut his testicles off.
Son: The horse or the jockey?

I'm still laughing as I type this. I can understand his confusion with the horse being named Cliffy. I don't know what these Pokemon games are teaching him, but that kid is hard core.