Well you would be stuck for ideas after conceiving everything but the kitchen sink. ;p
Actually, what about cooking?
You'd think so, but there are some very unusual and enjoyable events on (not necessarily in this society, but in some others) that attract a huge ground and go down very well. An "iron stomach" contest (Literature and Historical Society) where a huge selection of food is blended up with milk, cream, and butter into revolting smoothies that the contestants, situated on a huge stage with a sick trough in front of them, have to chug as quickly as possible to win. A "Mystery Tour Bus" (Science Society) where you go on a bus trip to some town, not being sure of the destination, to go on a pub crawl in an unfamiliar location, has also been rather popular with other groups. "Sumo Trampolining" (I don't know what society this was, only that it was on yesterday) was also a rather popular event that fell outside the more typical archtype.
A cooking based thing does sound like a good idea though. It'd probably have to be limited to dry ingredients (or else you'd have to organise things like finding grills, ovens, hobs, pans, etc. to use between over 400 members) but something could very likely be worked out in that I'd imagine which would certainly appeal to those not living at home.
Some degree of body hair can be nice, but I wouldn't personally be a fan of it in any significant quantity if I'm honest. The picture posted would probably be too much for me personally.