Ahh, good old bugs, back when cartoon where actually funny!
I've done that a couple times, I always feel like such a moron aftewards. I now always try to remember to check the windows and make sure they are rolled up.
I learned the hard way, about 30 years ago, to always check that the door is shut, locked, and window up when there was a passenger. No matter who is the passenger, trust is not part of my routine. All those years ago I gave a co-worker a ride to work. He left the side door unlocked and a very expensive camara that I had borrowed and subsequently had to replace, was stolen from the back seat.
Oh I pitty the foooooooo. LOL Your poor child. My sons have a friend that I always give a ride home from school. That boy always leaves the window open. Thankfully I see it right after I lock up the car. Say a few bleeps and re-open the door to close it. LOL