How the bee got his knees discusses spurious word-origin stories:
There are two specific kinds of mistaken etymology that continually recur. One argues that a given word has been created as an acronym, from the initial letters of a phrase. This is a common mistake, applied to words as widely differentiated as ‘cop’ (‘constable on patrol’), ‘posh’ (‘port out, starboard home’, from sailing-ship days), or ‘tip’ (money given to a waiter ‘to insure promptness’). People think this is a sensible sort of suggestion because we are surrounded by acronyms, such as Nato (‘North Atlantic Treaty Organisation’) and Sars (‘Severe Acute Respiratory Syndrome’). Some are now so accepted as words in their own right that few know their true origins: ‘radar’ is from ‘radio detection and ranging’, ‘laser’ from ‘light amplification by stimulated emission of radiation’, and ‘scuba’ from ‘self-contained underwater breathing apparatus’.The fashion for acronymic creation is a military one, dating from around the time of the First World War (an early example is AWOL, or “Absent Without Leave”, though even this wasn’t consistently pronounced as a word at the time), and acronyms didn’t get into general circulation until the Second World War and later. There are almost no examples of words of acronymic origin before 1900. Indeed, the very word “acronym” wasn’t coined until 1943.
Plenty of English words come from butchering foreign words:
Our minds search for familiar patterns and make mistakes. For example, when the second half of “bridegome” for the male half of a marrying couple became obsolete, people borrowed “groom” instead (making “bridegroom”). The Spanish cucaracha made no sense to English speakers, so they transmogrified it into “cockroach”. People translate the defunct word “umbles” for the innards of a deer into “humble”, as in “humble pie”. British Tommies in France in the first years of the First World War heard il n’y en a plus, “there is no more”, and condensed it into “napoo”, finished, done for, dead; they did much the same with ?a ne fait rien, it does not matter, which became “san fairy an”.