This was posted in the Less Wrong quote thread for August 2013. The attribution given is “Norwegian folktale”, nothing more specific.
Once there was a miser, who to save money would eat nothing but oatmeal. And what’s more, he would make a great big batch of it at the start of every week, and put it in a drawer, and when he wanted a meal he would slice off a piece and eat it cold; thus he saved on firewood. Now, by the end of the week, the oatmeal would be somewhat moldy and not very appetising; and so to make himself eat it, the miser would take out a bottle of good whiskey, and pour himself a glass, and say “All right, Olai, eat your oatmeal and when you’re done, you can have a dram.” Then he would eat his moldy oatmeal, and when he was done he’d laugh and pour the whiskey back in the bottle, and say “Hah! And you believed that? There’s one born every minute, to be sure!” And thus he had a great savings in whiskey as well.