Probably from the relative physical position of people talking to Uncle Ralph on the Great White Telephone.

Something that has survived from the past; An official who remains in office after his term; Disagreeable aftereffects from the use of drugs - The guest with the "hangover" (an ill feeling resulting from heavy consumption) may need to "hang over" (to lean over) the ship's railing. Etymology The term hangover was originally a 19th century expression describing unfinished business – something left over from a meeting – or ‘survival.’ In 1904, the meaning "after-effect of drinking too much" first surfaced. http://www.answers.com/hangover?cat=health 1894, "survival," from hang + over. Meaning "after-effect of drinking too much" is first attested 1904, on notion of something left over from the night before. http://www.etymonline.com/index.php?term=hangover "Hangover" --slang, describing the action of dangling over the commode (toilet bowl) the next morning . Simply put, hanging over the toilet to vomit the next morning. As Richard Roundtree stated on 1/03/00: "Verily, methinks the wench indeed hath quaffed of our finest ale; how apple-cheeked and lusty she doth appear!.....'til following morn when she hungeth over mine commode to rid herself of thine iniquities." But wondered (purely speculatively) if the term had anything to do with the habit of allowing prisoners drinks in all hostelries on the way to Tyburn to be Hanged...? HANGOVER -- n. 1904. The unpleasant after-effects of drinking too much alcohol. Originally U.S., apparently a development of an earlier usage, "something or someone 'left over' from before." From ""20th Century Words: The Story of New Words in English Over the Last 100 Years" by John Ayto (Oxford University Press, New York, 1999). http://www.phrases.org.uk/bulletin_board/38/messages/2123.html heavy, heavy hangover thy poor head The guests would take turns standing behind them and chant the rhyme, "Heavy, heavy hangover thy poor head, what do you wish this person with a bump on the head?" and as they said the word "bump" they would bonk the birthday child on the head with the gift they had brought. The birthday child would then 'wish' the giver something, usually something unattainable, like a horse or a swimming pool and proceed to open the gift. http://www.phrases.org.uk/bulletin_board/2/messages/75.html The Twopenny Hangover: This comes a little higher than the Embankment. At the Twopenny Hangover, the lodgers sit in a row on a bench; there is a rope in front of them, and they lean on this as though leaning over a fence. http://www.phrases.org.uk/bulletin_board/28/messages/179.html

After drinking, hanging over the toilet bowl throwing up.