Beer Fairy

I thought the tooth fairy was a pretty sweet deal when I was a kid, but she can't compete with the beer fairy! When I got to work this morning I noticed a package of some sort in the plastic, basket-type thing on my door. Hmm, an oddly shaped package wrapped in what appeared to be a rather thick, yet colorful, paper sack? Of course I started mentally reviewing all the students who might wish me ill, but that would have taken too long so I just opened up the bag to see what was inside. Turns out it was a bottle of Pete's Wicked Ale -- a fine beer. Questions:

• Where'd it come from?
• Am I supposed to leave an "offering" in return to see if the beer fairy will visit again?