This has happened three times now. The first time, we thought is was a fluke, but now we’re certain he’s doing it on purpose. He jumps a little, and lets fly, and it almost all lands on my son. I have three kids, and he’s only ever peed on the one, never on my wife or I or our dog.
We’ve had the rabbit about five days, we’re watching it for our neighbors. It’s a lop eared rabbit, male. In case it’s related, he’s pretty horny, having tried to hump my leg and knee a few times, and my wife’s also. Apart from the peeing and humping, he’s pretty friendly, and not afraid of anyone or the dog.
My rabbit used to do ti when he was pissed off, like he wanted out of his cage. I got him fixed (it was a bit pricier than getting a cat fixed) and he settled down a lot.
I’d guess, for what ever reason, the OP’s rabbit doesn’t like her son.