That's not really a dumb thief. It's just totally horrible luck, LOL.
Anyways, the best dumb thief stories have got to be the ones where the thief leaves behind his wallet which happens to have ID with his address on it.
My personal dumb thief story:
I was walking into a convenience store and passed by a couple kids standing outside the door selling Hersey bars for $2 each. I declined since I was only looking to buy some smokes, but when I walked out, I was a bit lazy in putting my change ($2) into my wallet and was just holding it in my hand with the bills flapping around. So I'm just about to pass the two kids when one of them yanks my change out of my hand and him and his buddy take off running. I stand there a bit confused, then calmly walked over to their candy they left behind and took all of it.
So they stole $2 from me, but I ended up with 60 Hershey bars.
Good deal IMO.