Here's the encyclopedia description--http://www.glitch.com/items/glitchmas-cracker/
In the interest of full disclosure, while you can't get Glitchmas Crackers from vendors now, I fully expect them to be made available next Christmas. They've been going for wildly inflated prices on auction lately, but not nearly what the strawberry seeds are pulling right now.
ETA--When I first posted this, there weren't any strawberry seeds on auction, so this was a very shot-in-the-dark offer!