I have mine in a pelican and i usually run it on top of the case. If it is really bad I can run it inside the pelican with the lid propped open but rarely do i do that. My laptop is pretty big so i also got a "scuba" like material laptop case that unzips 3/4 of the way around. I close my laptop and put it in that with the exhaust and cables unzipped. it offers good protection from a spill provided I act quickly enough.
Like the above posters I generally try to get a table or whatever is safest. If the crowd is really nutz can always just run DAT