"Lipidleggin'" is a science fiction short story by F Paul Wilson. It was first published in Isaac Asimov's Science Fiction Magazine in 1978.
Plot
The United States government has outlawed butter and untreated eggs because of their high cholesterol content. Gurney, an antiques dealer in rural New Jersey discovers several farmers who are producing the 'real stuff' and starts dealing in them, thus becoming a 'lipidlegger'.
A decade after the ban, Gurney is approached by an out-of-towner for his product, and only after showing the goods does the man reveal he is in fact a Health Department inspector - it is the equivalent of a drug bust. However, Gurney's insight reveals that the man himself enjoys buttered biscuits, but has not had one since he was a child. He is thus able to sway the man into eating one, upon which he accepts several sticks of butter as a bribe in lieu of the arrest, implying that he will become a regular customer of Gurney's.
As the story closes, Gurney makes note of a newspaper article about a planned ban on cartoons deemed "disrespectful to authority" such as Bugs Bunny, and slyly notes that he's already surreptitiously recorded the entire series, foreseeing a new black market.