He looks kinda sorry...
Not dog related, but once, my parents had about $10,000 cash hidden in their safe. My had a dehumidifier in the safe that required a small hole to run the electric cord out to an outlet. Apparently, the hole was big enough for a mouse to sneak into the safe. When they opened the safe for whatever reason, they found a stash of confetti instead of cash

Thankfully, most of the serial numbers were spared, and they recovered all but maybe $50.