There is one boy whom I remember from one encounter in Saranrom where he rubbed my crotch with one hand and tried to reach into my pocket with his other hand. Our paths crossed in Pattaya on my two last visits, and again he tried to reach into my pocket both times. This is the only incident that someone tried to steal from me*, nonetheless warning to my readers: beware if a boy is overly friendly. Unfortunately my recollection of the first two encounters is vague, otherwise I would provide more details.
*The stolen passport last year was successful stealing from me, and the drunken man begin of this year tried to rob me. And one attempt at stealing my mobile phone in Cambodia.