Good on ya for laughing! Sometimes that's all you can do to keep from screaming!
I learned about this problem the hard way. The first time I encountered it was with my brilliant but manic Border Collie. If she had done something wrong and you even looked at her sideways, she'd wet everywhere. This behavior is called
submissive urination, and dogs and wolves perform it as a communication of submission to an individual of greater standing. It basically translates to, "I'm not a threat. I have nothing to hide. Please don't hurt me." The problem seems to compound itself the smaller the breed; the only thing I can think of is that there's a smaller bladder there, and they may need to empty it anyway. This is just a convenient place and time to do it. It also seems to be a bigger problem the more intelligent and sensitive a dog is. So it's really a good thing! Ha!
Sometimes, yes they grow out of it. But Dugan, my Border Collie, did no such thing. So I had to adapt. Doog isn't stupid. She knows when she's done something I don't like. Dogs are master mind-readers. They study our body language, tone of voice, and even our smell to determine our moods, and they react in the way they think most appropriate. Doog long since grew out of her "badness", and now we're best buds. But when she does the odd bad thing, all it takes is a look from me to let her know I didn't like it.
So basically, I learned to be subtle in my signals of disapproval. If you bear down on a dog, yell, or sometimes even approach them straight on and rapidly, a lot of them will urinate. And, since Doog, I discovered Teddy, who will actually flip over on his back and squirt urine into the air like a fountain! He thinks he's being terribly polite. You need to do two things. First, learn to tone down your disapproval. Second, get the kid some training. He's the perfect age for puppy kindergarten. Go to PetSmart. He won't learn much, but you'll build up his self confidence and self esteem, which will show him that submissive behavior is unnecessary. It will also develop your mutual emotional bond, so he will feel he knows and understands you better. Then, get these books:
The Complete Idiot's Guide to Positive Dog Training by Pamela Dennison, and
The Other End of the Leash by Patricia McConnell.
PS - I LOVE Minpins!
