Haggis is a traditional Scottish dish, celebrated as a mark of Scottish identity (the 'great chieftain o'the puddin' race'). Originally, it was prepared by boiling the the liver, lungs and heart of a sheep, mincing the result and mixing with chopped onions, toasted oatmeal, salt and pepper and stock, stuffing the mixture into a sheep's stomach, and boiling again. These days haggis is generally prepared in a sausage casing, rather than a sheep's stomach. Oddly, there are vegetarian versions.
Haggis is commonly accompanied by "neeps and tatties" (boiled swede or turnip and potatoes, mashed). It is served as the main course of a Burns supper (on 25th January every year). In formal suppers, its entrance into the dining hall is accompanied by bagpipes, and its ingestion is accompanied by liberal amounts of whisky.
A "haggis supper", as bought from fish and chip shops in Scotland, comprises a haggis deep-fried in batter with an accompaniment of chips (fried potato wedges) with, according to taste, a sprinkling of 'sat and sass' (salt and sauce - comprising a mixture of vinegar and brown sauce). Scotland has one of the highest rates of adult obesity in the world.
The USA banned the import of haggis in 1989 as a precaution against bovine spongiform encephalitis (BSE, or 'mad cow disease'). The ban was lifted in 2010.