JA Konrath

S.A. begins with a most unhappy --but healthy-- gentleman crossing a snowy parking lot, carrying a semi-see-through, blue plastic box containing a large stool sample. In fact, it's not a sample. It's the whole enchilada.

He's taking this vigorous specimen to his doctor because there's something unusual about it. There are buttons and coins embedded in it. Now, it's nothing like that health insurance advert where the patient has money coming out of the wazoo, as the western oriental ER surgeon explained when making one of those predetermination phone calls.

The coins are small change. The doctor's advice about unhealthy midnight snacks is... priceless.

After a thorough rectal exam which brings to light many strange things and leads to some unpalatable conclusions in the mind of our hero, he waddles off to search the internet for clues as to whom he's been eating when the moon is full.
Just when I thought I'd read every dragonish permutation of bad people tasting good (or bad), or good people tasting bad (or good), JA Konrath comes up with a fresh twist.

This story is a riot. I laughed out loud three times in the first three pages. Of course, there are certain bathroom words that will make me laugh out loud. One of them is poop.

The would-be sci-fi writer in me appreciated the elegance of JA Konrath's solution as regards mass. The hero has a mind-boggling telephone conversation with a were-squirrel... who collects nuts... and he asks both questions that spring to mind, much to this reader's delight.

I'm not going to tell you what 'S.A.' means, because I enjoyed guessing.
Poop is a very good place to start, when one is creating a convincing werewolf. Done right, starting with the scat is an excellent short cut to world-building.
Jacqueline Lichtenberg advises world-builders to start with the sun. But for a short story about a magical being, why not start where the sun don't shine? I'm not a gentle reader. I don't suspend disbelief easily. I'm not programmed to trust my author, no matter how outrageous. Not at first, anyway.

I can give a turd the benefit of the doubt for several reasons. For a start, the narrator is embarrassed about it. That's believable. He's also frightened. He's not Mike Rowe (of Dirty Jobs), so he's probably not inclined to put it through a sieve.
If there are bits of teeth, chips of bone, coins, buttons, a crucifix, a clump of dead man's beard... I get the picture. I don't worry about the force of a werewolf's bite, or his stomach capacity, or the inhuman speed of his digestive processes whereby the indigestible evidence of his midnight feast ends up in his morning toilet bowl.

I found SA hugely entertaining, although the short tale did plunge into farce, horror, sweet romance, and heart pounding action. Perhaps a little too much was packed into 50 pages, but it was great fun.