köken: From petit (“small”) + juif (“Jew”). Allegedly the expression came from the time when most cloth merchants in France were Jewish, and would regularly hurt their arm on that spot against a bench while measuring fabric by wrapping it around an arm as an 'anthropomorphic' length measure, the aune (compare ell).
köken: Original derived from änkemansstöt; änkeman (“widower”) + stöt (“thrust, blow, strike”). According to Nationalencyklopedins ordbok the word is the result of a contraction influenced by the idiom änkemanssorg och armbågestöt går snart över (free translation: "a widowers grief and a blow to the elbow are soon forgotten"). Attested since 1923.
Jag träffade bordet med armen och fick en rejäl änkestöt.