But The Hangover was such a phenomenon because of good word of mouth.

FORBES: 'The Hangover Part II' Has Big Shoes to Fill

"Thus, while hangover is a common phenomenon among college drinkers, for most of them it occurs rarely enough that it is unlikely to have a major deleterious impact on academic performance, " Dr Slutske said.

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The hangover is an astonishingly complex physiological phenomenon, with dozens of symptoms and relatively little human trial data - rats and a few undergraduates are the preferred model for much of the relevant research.

BBC: US chemistry meeting tackles science of booze