"Dear little boy or girl,
"First and foremost, I am sorry for any grief I have caused in the last couple of days but I am now trying to return your bike to the proper home where it belongs. You see, I stole your bike the other night purely out of selfish convenience and due to my state of inebriation I cannot recall exactly which house it was in the vicinity of this neighbourhood. I think the lesson to be learned here is that you should NEVER leave your bike out in plain view where drunken fools like myself can easily snatch it for a quick (and surprisingly fun) ride home.
"Sincerely, Anonymous Drunk Thief"