Nigella Lawson recently tweeted a recipe for what she called 'slut's spaghetti' (her recipe here), a translation of the Italian spaghetti alla puttanesca (Italian for 'in the style of a whore'). Nigella says that the dish is so-called because it is "the sort of dish cooked by slatterns who don't go to market to get their ingredients fresh, but are happy to use stuff out of jars and tins"; (she also goes on to recommend, with tongue in cheek, "serve in slatternly style, preferably with an untipped cigarette clamped between crimson-painted lips"). That definition serves her purposes for creating an easy recipe, but other commentators and sources disagree on the reason for the name.
The Wikipedia page suggests that the name derives from the Italian puttanata, rubbish, and came about after a chef cobbled together a meal out of a few leftover ingredients in his cupboard, after he'd run out of fresh vegetables.
The OED says it is unclear why whores are linked with the dish, although it concedes that puttanesca does derive from the old word Italian word puttana, prostitute. There are other posited origins, including that it derives from a proper name, or from an old Tuscan word for spicy or hot, but there is no evidence for these theories.
I have written on the English word slut before (here).