On Dogs and the Barter System

So I'm sitting at my computer, just finishing a bowl of cereal that I had for my breakfast. Murphy wanders in and tries to nudge up against me as if to suggest that I should let him have some cereal too.

"Oh, hell no, dog," I tell him. "This is mine. You have your dog food, and I don't eat that, so you're not eating this."

Murphy wanders back out of the room as I knock off the rest of the cereal and set the bowl aside on a chair next to my computer desk. I don't think too much of it when Murphy comes back in a minute later with one of his favorite toys, a small stuffed horse. He walks up to me and places the little horse in my lap.
"Why thank you," I say, taking the horse, figuring that he wants to play a bit. But instead of trying to get the horse back, he walks over to the bowl and begins to lap up the milk and cereal residue. Then it dawned on me: we just did a dog-initiated trade here--his toy for my food.

The damned dog just came in here with the only currency that he possessed and "bought" my bowl of cereal. Offer and Acceptance. I guess he wins.

Note to self: Move the law books in my office to a higher shelf. Someone's obviously been reading the one on Contracts while I've been out.

"Next I trade you this pig ear for yur car keyz."