How shatterproof is a shatterproof glass?

A ten ton feather?

Okay what did I win for getting the right answer?

If you could shatter it, it is, by definition, not shatterproof. I remember a riddle from my youth, "What happens when an irresistible cannonball hits an immovable post?".

Actually, shatterproof glass can break, like car windshields. It's just that when they break, a thousand pieces don't fly off into the air and injure somebody. But the break will be there.

What is the specific instance of shatterproof glass you are interested in? Cell phone?

I am referring to shatterproof glass in windows.
"If I am to throw a regular size hammer into it will it break" that kind of stuff.