One of the gastronomical delights of British cuisine.

Take two slices of bread, preferably white and thick-cut. Lavishly coat them with butter (note, margarine will NOT do). Place chips between them. For the linguistically-challenged out there (ie Americans), chips are thickly-cut deep-fried fingers of potato, kind of like fries but far far better. Anyway, fill the space between the bread slices with chips, coat in lashings of HP Sauce and devour.