Wait, I'm confused about what you were testing. You thought that glass didn't break???
I was not testing anything, I was not paying attention and was squeezing my glass. Before this I never thought you could squeeze it to break. Figured it was to strong.
Two things you should know, if you didn't already:
1) Glass does break. If you're that absent-minded about squeezing your drinkware, consider getting polycarbonate vessels instead. You can drop them on concrete and they won't break, and they look just as nice as glass.
2) On TV, they DON'T USE REAL GLASS. When a glass breaks, except for the rare accident caught on film, it's usually something I mentioned earlier - candy glass. Candy glass is just what it sounds like - it's rock candy, but shaped and polished to have the appearance of real glass. It will even hold a beverage for a limited amount of time. Crush it in your hand, shatter it over your head - no real ill effects to speak of. You literally can eat the remaining pieces - it's made mostly of sugar. Mugs, bottles, even windows can be made of the stuff. I'm told it's not very cheap, but it's a whole lot safer than breaking real glass.
Ever watch an older movie or TV show, when someone shatters a piece of car glass and instead of breaking in a sheet like safety glass is supposed to, it breaks more like an ordinary window would? That's because they replaced the window with candy glass specifically so it can be broken.
I actually managed to intentionally break a car window once, barehanded. I was young, foolish, drunk and lucky - didn't even so much as scratch myself, never mind creating a real wound or breaking a bone. It's not something I'd recommend anyone should attempt, but at least I know how it's done...