Stingy about small expenditures and extravagant with large ones; for example: Marian clips all the coupons for supermarket bargains but insists on going to the best restaurants—penny wise and pound foolish. This phrase alludes to British currency, in which a pound was once worth 240 pennies, or pence, and is now worth 100 pence. The phrase is also occasionally used for being very careful about unimportant matters and careless about important ones.

Where someone compulsively saves money by buying super-cheap-priced foods like crackers and white bread, not caring/realizing that these salty/sugary/"empty-carbs" foods will make him gain unhealthy weight in a hurry. Ben Franklin was always sagely expounding about stuff like this, and just look at da deplorable "tubby" shape HE was in!