This St. Patrick's Day, ask yourself this: What are we celebrating? If you are like most people, you probably don't have a confident answer and find it annoying that someone like me is killing your green Mardi Gras buzz by raising the issue. Are we celebrating nationalism? Christianity? Alcoholism? The vanquishing of snakes? Things were a lot simpler when I was a midget: St. Patrick's Day was mostly about shamrock shakes. Sad but true.