Classroom Management... Wouldn't it figure?

Today is Parent Open House on our campus. What this means is that the parents can stop by classrooms today and watch classes in session. This gives parents a better idea of what an actual class day is like. I've had about six parents come by so far. Two I know were parents of students I have currently, but I'm not sure about the other four. Some parents from our feeder schools even come by today to get an idea about what classes here are like. I don't mind them visiting. What I DO mind, however, is my second core being totally rowdy, unfocused, and off the wall to start class when two parents are watching. I was torn in my brain as to how to handle it. Do I get mad? Do I yell? I thought it was best to avoid those two scenarios, so I tried to put out spot fires as best I could - targeting specific students and asking them to stay focused, stay quiet, get back on task, etc. But this didn't really help. When the parents left, I let the kids know how I was feeling. Can you imagine what those parents were thinking? I asked them. One kid replied, "That we're horrible students, you're a horrible teacher, and this class is horrible." Yup, about sums it up. "Do you want adults to think that about you and me?" I asked them. A lot of them looked petrified at the idea. I'm glad that our candid conversation sort of drove home the idea that not only does it embarrass me, but it makes them all look bad as well. Hopefully the next time other adults are around, they'll be more conscious of that. How would you have handled the situation?