To all of you saying another universe (or ours), I hope Terry Pratchett's explanation is what you're hitting on. Inside the box is Discworld, a very strange place where magic is real, and things exist simply because people believe in them (gods for example wax and wane in power, or indeed pop into and out of existance based on the amount of belief in them). And within Discworld is a small snowglobe, containing Roundworld (our Earth). And thus starts a paradoxical cycle of questions of which universe really contains the other...that the wizards of UU couldn't care less about, and would rather get on with dinner.
But to answer your question, mine contains Pokemon Soul Silver :3.