I have heard this is not too uncommon. What is the function of this behavior? From my experience with a child who has done this for years, this behavior is not an accident. He will urinate onto his bed, under his bed, onto the walls, and into containers instead of just walking to the bathroom a few feet away. He'll urinate all over the bathroom purposely not in the toilet. It is an enormous problem because they can't take him anywhere.
It isn't for attention, because he tries to hide it and lies about it. Since this is apparently a behavior not atypical for kids who come from abusive or neglectful backgrounds, what is its function? I have yet to find anyone who knows.