Do you need a hammer along with the ballpoint pen?
:clap::clap: For those people that stopped!
A pointed object works on the same theory as cutting a diamond. Diamonds have a kind of square internal crystal structure (I know that's not the correct geological term, but...), so while they're known for being hard to scratch, they're fairly easy for a jeweler to cut. Except it's not really "cut," as much as it is "break." You put a pointed object in the right spot, tap, and it tends to break cleanly along the planes. That's why you can get so many facets in a diamond, because it has an internal structure with lots of square plane surfaces. As opposed to, say, an emerald, which doesn't have the same kind of orderly internal structure--hence the big square-topped "emerald cut," because trying to facet an emerald will often just result in it shattering. (Which is also why large emeralds tend to be more expensive than, say, large sapphires--they're harder to cut. Plus, when they find a honking big zillion-carat gem in a mine somewhere, it's usually a sapphire and not an emerald--emeralds shatter too easily to be that large.)
Car windows are made of tempered safety glass, designed to break into little cubes rather than into shards. So using a punch is the same kind of principle as when the jeweler "taps" into a diamond--theoretically, it should break all of the little cubes apart, like when you use a wedge or the point of a chisel to split a log. Or like those Chocolate Oranges you get at Christmas, where if you whack it on the end, it will cleanly break open into equal "slices". Car windows have gotten a little tougher to break as they've gotten more anti-theft, though, plus people tend to panic when they're in a situation where a car window needs to be broken. Mythbusters did a show on what would and wouldn't work to break a car window in an emergency:
http://mythbustersresults.com/episode72
Sorry to get all off the topic with a lecture on gemstone structure and glass-breaking, but I live in a area with a lot of lakes and ponds, and people are always accidentally driving into ponds and lakes and then dying because they're unable to get out. (I can't imagine anything worse than being trapped in a car while it fills up with water. Except maybe being trapped in a fire.) You can get a little device called a center punch that will break the side window. Even better, you can get one that's kind of a small punch/hammer hybrid, with a seatbelt cutter on one end. (Because people freak out and can't remember how to get the seatbelt off in an emergency.) They're not that expensive, so everyone should have one under the front seat of the car or in the glovebox, or you can even get smaller one that go on your car keychain. I give them as Christmas gifts a lot...which makes people think I'm pretty odd, because I think it probably ranks up there with underwear and socks on the Undesirable Practical Gifts scale. But hey, one day it might be the best gift that person ever received. And in keeping with the theme of this forum, who knows, maybe one day someone will be able to use one to break out a car window and get away from a serial killer or something.
http://saveyourlife.us/LifeHammer.html
http://www.resqme.com/
And, uh...back on topic: I have alerted security when someone left a baby in the car in the dead of winter. I was leaving campus late, and while I was walking to my car, I saw something move a bit in another car, and it was a baby in a car seat. I'm guessing a student couldn't find anyone to babysit, but didn't want to miss their once-a-week night class, so decided to leave the baby in the car and hope for the best. But our night classes are almost 3 hours long! And it was in the furthest parking lot, so I don't think there was much chance that someone just left the baby there while they ran in to turn in a paper or something. (Which would also be unforgivable.) Whoever the parent was, they probably parked as far out as possible so the car would be away from the parking lot lights and no one would notice the kid. Idiots. I jotted down the license plate number and then went straight to get campus police. I just don't understand people--it was the middle of winter, and I live in the snow-and-ice-storm midwest. I'm a stickler for attendance, but I always always always tell my students that there are lots of things that are more important than a grade in a class. And your kid's life is one of them. Geez.
And now, back to my habitual lurking mode...