24 pack of Coke I believe. I've never seen them in stores and I can't seem to find them online.
From what I read in an article, the House Party people don't like to choose the same people frequently. They don't want to have the same people repeatedly hosting parties. So, eventually you'll get your chance, so maybe it's best to sign up only for things you really want otherwise you'll end up getting a Boboli party and being passed over for something better.