Car hopping - I didn't know it had a name but it's rummaging through someone's vehicle for valuables. At its most innocent, it's testing if the handle is locked. If it's not, you just grab whatever cash you need. It gets worse, of course.

It happen to me but it was a window smash. Nothing at all taken from my car but everything was rifled through. A neighbor recently had their insurance/registration swiped and nothing else, no busted anything.

There are a lot of people who don't lock vehicles for myraid reasons. There are also lots of people willing to slyly slip in and out of those unlocked vehicles. Do it right and pretty much no one will notice you doing it