Guilty Until Proven Innocent

But mother, those aren't cookie crumbs,
  They're fragments of my drying tears.
If I have chocolate on my thumbs,
  It may have been there many years.

Your accusations are unjust.
  The evidence is circumstance.
I always strive to earn your trust,
  But you won't give me half a chance.

Just look inside the jar, you'll see
  The cookies are accounted for.
Perhaps you stored them carelessly,
  And bite-sized chunks fell on the floor.

I won't surmount your scrutiny,
  You've made your mind up, I assume,
So I'll accept my penalty,
  And bide my time within my room.

But mother, there will come a day,
  When I am grown and live afar,
That you'll no longer have a say
  And I'll control the cookie jar!