I accidentally fed a slug into a full choke shotgun and blew the barrel apart.

That was at age 12.

No physical injury, but my father was sure pissed off after he got past the "Ok, the boy is not hurt" part.
He was more upset and pissed because I did not follow the basic rules. "Always ensure that the ammunition is fresh and correct for your weapon".

Then I spent what seemed like forever working and saving to pay him back for the replacement Auto-5 Barrel.