Sorry guys, have been moving house...
mathmo - Knowledge of the material would be largely unhelpful except to know that the box isn't airtight. In this case it's a cardboard box, wrapped up with tape.
I don't know where the box is from, and I don't have any special powers.
Xell101 -
1. I hope you're not accusing me of killing kittens!? (fap fap)
2. How did you guess??
Nope, not a penguin or anything to do with Superman. In fact, this is quite a realistic situation (except for the fact the box contains an ex-cat)
3. No mail-order involved, but I like...
4. Until I picked up the box I had no idea what would be in it.
collide - the box is still closed; nice try though. And no card to tell me.
fresprite - I didn't put the cat in the box, or see it being put there, or otherwise know of it being there in advance of actually receiving the box.
Keep going guys! I may have to start dropping hints...