From my MA experience, I felt the exact same as most people in this thread- stupid for the first two weeks. Most people were giving answers that were eerily similar, while I had different ideas that I was hesitant to express. However, when I started expressing my views, students and professors were amazed at my ability to see things that the "common" student didn't see.
I agree with what daydreamers' friends said- contribute something unique. Remember, an MA program is not the same as a BA/BS program. BA/BS programs are concerned with learning information more in a black and white way. MA programs want to provide you black and white, but have you explore the gray- this is why it's not easy and gives many people a hard time. Once you learn to embrace the gray, back up your view with sound experience or information, and understand thinking different is an asset and not a hindrance- you will be fine.
It is my personal opinion that MAs are for exploring concepts that are a mixture of right and wrong. You are not stupid for not knowing what others know, nor are you unqualified to be there because your answers are not as polished. Shift your focus to what you bring to the table and not what everyone else has on the table.