Where do they get that ...

Is it worse to wonder where your kid got an idea, or to know exactly where he got it?
Two examples:
Big Boy's new thing is to run away from me when it comes time to put his diaper on. So yesterday morning, he's running away from me, I'm chasing him, and he runs between the coffee table and the couch. He's laughing, "Ha ha ha, ha ha ha," and then he says, "God damn it," and then keeps laughing. "Ha ha ha."
In this case I know exactly where he got that. It's MrDartt's standard exclamation, whenever something happens. He drops an ice cube when filling his glass. (Every single time he fills his glass.) "God damn it." He hits his hand with a hammer. "God damn it." He is mad at Big Boy. "God damn it."
The second example comes from one of my closest friends. Her son is three, and they also have a seven-month-old girl. Well, to speed up the bathing process, one parent sometimes jumps in the shower with both kids. The baby sits in her little bathtub on a big step in their shower. They use a little cup to rinse her. The other day when my friend's husband was bathing the kids, the three-year-old, who's been potty-trained for quite some time, picked up the baby's rinsing cup and peed in it! He set it down, full of pee.
The worst part, my friend said, was that the baby would have gotten rinsed off with it if my friend hadn't seen the whole event and dumped the pee.
She has no idea where her son got that idea.