Good chance it's their work van and they're on the clock, lol

"Oi, what happened to the windshield?!" "Bloody truck kicked up a stone and got it good, boss!" "Oh, well, better get it replaced"

It's all fun and games until you find out your boss and the local Carglass owner are drinking buddies. "What the hell are your guys up to that they cracked the windshield from the inside?" "The what?"

It doesn't take much to crack a windshield from the inside. Not dismissing his skull, but a decent slap (think swatting a mosquito) could do some damage. (Not speaking from experience, buzz off) I'm guessing it's something about eggs and domes and how force gets transferred

I wouldn't pull this prank. But I found it funny because they found it funny.