An Etymological Dictionary of the German Language/Annotated/schleudern
schleudern, verb, ‘to perform in a slovenly manner, bungle’; it is not really related to the preceding word, though it is instinctively connected with it by Germans, in Schleuderpreis, ‘undervalue,’ for example. The verb is allied to Middle High German slûderer, ‘he who works hastily and negligently,’ which again, with an excrescent dental (as in haudern), is akin to Middle High German slûr, masculine, ‘bungling, idling, idler’; compare Schlaraffe and schlummern.