with us its a variation on 'it all went pear shaped' and if anyone can work that one out let me know, cause buggered if I know S
wiki: The oldest usage from the Oxford English Dictionary (OED) is the most literal, a 1731 reference in a gardening dictionary comparing the shape of the fruit of the cashew, or avocado to that of a pear. The comparison is less literal when the term is applied to people, where it means wide at the hips, a use that goes back to at least 1815, and one that can have either positive connotations (as in Venus figurines) or negative, depending upon the context. In the 20th century, another, more abstract use of the term evolved. When said of someone's voice, "pear-shaped" means rich and sonorous. The OED dates this use to 1925, though a more recent example comes from The Thorn Birds. Colleen McCullough, the book's Australian author, uses it to describe a change of the tone of the voice of Father Ralph, one of the major characters of the novel (the one played by Richard Chamberlain in the miniseries adaptation). The third meaning is mostly limited to the United Kingdom and Australasia. It describes a situation that went awry, perhaps horribly wrong. A failed bank robbery, for example, could be said to have "gone pear-shaped". The origin for this use of the term is in dispute. The OED cites its origin as within the Royal Air Force; as of 2003 the earliest citation there is a quote in the 1983 book Air War South Atlantic (ISBN 0-283-99035-X). Others date it to the RAF in the 1940s, from pilots attempting to perform aerial manoeuvres such as loops. These are difficult to form perfectly, and are usually noticeably distorted—i.e., pear-shaped. The phrase first came to the popular media when being commonly used in the British drama series The Bill. Other theories include: If the original plan was to be visualized as a perfect circle, then the failed execution might be pictured as a distorted figure, hence "pear-shaped". Some aircraft engines become distorted (pear-shaped) in the event of failure. Early biplane aircraft buckled into a pear-shape when they crashed, especially stalling on take-off. The phrase refers to the shape of a gas balloon when it loses pressure. Gas balloons are spherical due to aerostatic pressure, but when they leak the gas rises to the top of the balloon and the neck bunches up, causing the balloon to look like an upside-down pear. The phrase hails from Victorian England when gas balloons first became popular. In statistics, when the shape of a normal distribution widens, it becomes less of a spike and more of a dome-shaped distribution with flanged edges (like the top half of a pear). Thus extreme outcomes that were very unlikely before are now much more likely, and unexpected events may well occur. This explanation is very unlikely, as most statisticians refer to the normal distribution as a bell-curve, not a pear-curve. In glass blowing it describes a failed circular blown vessel. If over heated the glass becomes too fluid and distorts under gravity as it cools, resulting in a pear-shaped vessel. This was particularly important with early experiments with cathode ray tubes, where creating a large spherical glass vessel was necessary. Blowing such an object was a challenge and often 'went pear shaped'. It refers to the shape of a pregnant or obese woman. It refers to the shape of the Earth, a (very slightly) lopsided ellipsoid. It may be a mechanical engineering term: White metal bearings (large stationary engines and the like) when worn become "pear shaped" sometimes, due to wear and tear. It was also used to indicate poor workmanship in the manufacturing.
