(Pickle Fairyis clumsily dancing away this fear, Thu 7 May 2009, 13:13,
archived)
it's the brown sauce they have in chippies,
that they add vinegar to whenever they start to run out of it, presumably on the understanding that it "makes more of it".
(Moon Girl Technologieshorrendous beanbag, Thu 7 May 2009, 13:16,
archived)