Kat: I think most people are shy. Truly, I know that I am. No one really believes that but I still am in lots of situations. Josh is. My kids are. Yet all of us handle ourselves well as adults.
Like Mish points out - those that were the really "cool" people did a lot of things in high school to "BE" cool while some us chose to do things that were considered more "uncool" but we still stayed true to ourselves. I danced all through high school although very few people did and I was sure they'd make fun of me. Then the principal asked me to twirl baton in front of the school. I was terrified but agreed to it and guess what? Some of those really cool people told me how much they wished they could do what I did. LOL
It's funny but we all seem to be on the same playing field when we grow up. FB does tend to break some of the ice before the reunion so find out from there who will be there, who you can sit with etc.
Who knows? You might find a single guy you went to school with that you now find "hot".