I had a small short hair Pomeranian-Chihuahua mix we called 'Bear' (he thought he was big and tough, but only stood 10" tall).

One day he ate an entire pop can. Pulled it out of the recycling, shredded it with his teeth and ate most of the pieces. All he had left was the top when we found him and took it away; he couldn't quite get through the rolled edge, so he couldn't break it down enough to swallow.

Somehow, he was perfectly fine. Didn't go see a vet, wasn't bleeding or showing signs of pain/illness. We did find a few shiny pieces in his poo while cleaning up the backyard...