How DOES that glass get there!?

The same thing happened to my boyfriend when we were eating at a Red Robin restaurant last month (I'm not sure how big of a chain this restaurant is because it is relatively new in my town). We went with his parents and we always go to a fairly decent restaurant when they come into town. It was extremely crowded for a Tuesday night; there were several birthday parties or something, so we had to wait fifteen minutes before we could be seated. We sat at the bar and ordered drinks, and my boyfriend ordered a beer. After fifteen minutes, we were finally able to sit down and order our meals. During the meal, my boyfriend finished his beer and his mom noticed that there was something sitting at the bottom of his glass. At first we all thought it was ice, but then I said, "Why would someone put ice in a beer?" Turns out, it was a large piece of glass. Of course my boyfriend's mom becomes irate, waving a waitress over and yelling at her. The rest of us become a little embarrassed at her antics because the poor waitress is confused, apologizing profusely for something she had no control over. She explains to us that at the bar, all of the glasses are set upside down until they are used, so she had no idea how that piece of glass could have gotten in there. She brings the manager over and my boyfriend's mom explains the situation. The manager didn't seem to care whether or not my boyfriend could have choked and died on that glass. She offered to pay for all of our drinks.
I think in this situation, my boyfriend's mom overreacted, but the manager of the restaurant underreacted. We haven't been back to the restaurant since. I doubt my boyfriend's parents will be back at that restaurant; I'm not going back there again but that's only because I didn't like their food.