If the lettering is difficult to read, here's what it says: How to play: Do not tear this package. Find the object.Break the small water-bag inside the package which will be full of air immediately.Drop the bag beside the object. When the bag pop and the stinking will Full the air. Eating prohibited.
How to play:
11 July 1998:Upon returning from a Burning Man meeting, I found this item in my mailbox.
(Thanks -- or blame -- goes to Babs on this one.)