What can they actually do to you if you don't go to NSM?

I've asked this a few times but I've never gotten any sort of real solid answer. Does anyone have direct, first hand knowledge of what happens if you say "Nope. Not going." I hate it for a variety of reasons, but last year I got crazy bad food poisoning after the first night's little pep rally thing, and I'm not going again. What are they going to do, fire me for staying home and doing my job? REAL ANSWERS ONLY.