Confusing confessions

As the kids get older, they get more rough with one another. I am sure this is seen in every household with siblings around the world. The funny part about their age and knowledge of words is that they don't know when they are telling on themselves. For example, Jacob yesterday was explaining to me why Andrew was crying.

I asked him, "What happened to make Andrew cry?"
J: "I on purpose hit him with my truck and then he started crying, but then I said I was sorry and he gave me a hug."
I said, "Do you mean, it was an accident that you hit him?"
J: "No mom, I on purpose hit him."

I am still confused if he knows what he means. If nothing else, at least he told the truth.