Topic related bonus mini-story!!
Many years ago I was driving home through a residential area and was pulled over by a police officer. I parked and stopped my car, found the registration in my glove box and rolled down the window. The cop walked up and asked "Do you know why I pulled you over?"
Now the correct answer to this question is pretty much always "No officer, I don't know" said with just as much innocence and sincerity as you can manage (and if you're a girl and can toss a hint of tears in there, go for it). I say pretty much because if you were doing 90 in a 25mph zone while swerving to hit grandmas you're just going to piss the cop off by playing innocent, but unless your offense was blatant this is the way to go.
However, I was relatively young and freaked out so I said "Well, I was going a bit fast." (probably 30 in a 25mph zone)
The officer smiled at me a little and shook his head but didn't say anything. So now, I should have gone for the "I don't know" innocent look and quivered my lip a little. Instead I said "Um, I kind of rolled through that last stop sign but no one was around."
Again, the officer said nothing. Again I didn't break out the 'I don't know' but at least I stayed quiet, mostly because I couldn't think of any other reason he could possibly have pulled me over.
"Your registration is past due. I am going to write you a fix it ticket but as long as you get all the paperwork taken care of it should be fine." (I had problems for the first few years I moved back to CA because some genius in the DMV had inverted two of the numbers in my street address so none of my mail reached me.) He walked back to his car to write out the ticket, and I slumped in my seat.
He came back a few moments later and handed the ticket to me through the window. "And, you might want to drive a bit more carefully from now on." I nodded emphatically and watched him get in his car. I pulled out carefully and drove 3 miles below the speed limit everywhere, for about a week. And I learned that sometimes "I don't know" is the very best answer you can give.