Jerry (n.) Look up Jerry at Dictionary.com
World War I British Army slang for "a German, the Germans," 1919, probably an alteration of German, but also said to be from the shape of the German helmet, which was thought to resemble a jerry, British slang for "chamber pot" (1827), this being probably an abbreviation of jeroboam. Hence jerry-can "5-gallon metal container" (1943), a type first used by German troops in World War II, later adopted by the Allies.