A label used at the University of Southern Maine to describe someone who believes the right side of the cafeteria is somehow superior to the left. They are unwilling to accept people (mainly "left-siders") for who they are simply because they are not like them. Many freshman will quickly realize that the real world in full of diversity and labeling yourself as strictly "right-sided" should only be applied when talking about brain functions.
Joe: Man, do you see those left-siders over there?? They are so weird! I'm so glad I'm in my mid twenties and proudly call myself a right-sider at USM, the best school ever.