I smashed a window at school when I was about 12/13 by trying to slam it shut so the window handle hit the person behind it (not in a serious way, just in a messing about way).
The window didn’t entirely smash but I kind of felt I should let the teacher on duty know what I’d done.
I was shitting it because he was one of the strictest teachers there.
When I told him, he growled at me that he’d come and take a look.
Upon inspection he said that he’d have to remove the glass from the frame as it was unsafe and went to retrieve a sledgehammer (!) to do it.
He removed the glass using the sledgehammer, which cracked the window next to it. So he removed the glass from that window too.
By the time he’d finished, he’d removed three whole windows from the side of the classroom.