Not to blame this on teenagers, but certainly, folks must realize that "carhopping" is a common teenage activity. (Not a good one, and you would be surprised at just who all has been implicated at times.) Two summers ago, a pack was broken up that had frequently targeted Baytowne, Grand Blvd, Mack Bayou and Grayton. There was at least one incident in Seaside last summer (perp got caught), and back in March/April (I forget the date now), ShallowsSquirt left his backpack in the back of the truck while spending the night at a friend's house on Morrison Street and by 9:00 p.m., the contents were all up and down Bay Drive. The backpack showed up the next afternoon, hung on a Bay Drive mailbox. Interestingly, the perp didn't take the digital camera that was in there; they got to the dirty gym socks and stopped.
It would take gonads to steal stuff from our house as being shot on sight is a distinct possibility, but it has happened. One day a couple of years ago, when we were all at work (save for ShallowsSquirt, who saw the event but didn't want to confront the bandit) an aluminum jonboat was taken from our front yard. ShallowsFuzz put out a large sign asking the thief to bring the boat back. It came home a couple of days later, with a new coat of paint and watersealed (thanks, thiefs).
I hate it too, but we lock our doors...