In Discworld, Scumble is an exceptionally strong spirit, made from apples. Mostly apples. Drinking even the tiniest portion of it will make even a knurd imbiber drunk. Drinkers on the disc don't appear to be too careful about their beverage quality or consistency thus we know of no reliable measurements of its potency, but we can infer that scumble is at least 240% alcohol. It is said to taste something like apples, something like autumn mornings, and an awful lot like the bottom of a log pile. Apparently it cleans spoons, but it's not recommended. It's not recommended that it touch metal at all, or anything else for that matter.