That happened to me once and almost happened a second time.
First time was about 5 years ago. The guy hopped in and mumbled something about how if I knew what was good for me I'd listen to him and just drive. My response was a 6 1/2" Model 27 that I just happened to have with me. I cocked it, his eyes about popped out of his head, he went clawing for the door handle and upon opening it literally fell out of the truck (85 Ford lifted 6" on 35's) and started running.
After that I learned the lesson about locking my doors, but keeping the windows up wasn't an option. No A/C sucks.
Most recent event was about a month ago. Pulled into a stop and rob to get something to drink. Got back in my truck (locking the door as soon as I got in) cracked the window, then leaned over to roll the passengers side window down (have A/C now, but it was a nice night).
As soon as I leaned over I heard someone grab my door handle. I had an SP101 appendix crossdraw, cleared leather and looked back at him while still leaned across the console.
His first response was to put his hands where i could see them and jokingly say with a goofy grin, "Hey, bro- don't shoot me." (he didn't realize I was armed since i was leaning over the gun)
As I sat up light glared off of the stainless and it looked like he about soiled himself
Funny thing is I had a bad feeling about that guy as I walked in. Not any of the others he was hanging out with, just him. Made sure to keep an eye on him. Strange how stuff like that goes down.