applesauce (n.)youdaoicibaDictYouDict[applesauce 词源字典]
by 1739, American English, from apple + sauce. Slang meaning "nonsense" is attested from 1921 and was noted as a vogue word early 1920s. Mencken credits it to cartoonist T.A. ("Tad") Dorgan. DAS suggests the word was thus used because applesauce was cheap fare served in boardinghouses.[applesauce etymology, applesauce origin, 英语词源]