balderdash (n.)

1590s, of obscure origin despite much 19c. conjecture; in early use "a jumbled mix of liquors" (milk and beer, beer and wine, etc.); by 1670s as "senseless jumble of words." Perhaps from dash and the first element perhaps cognate with Danish balder "noise, clatter" (see boulder). "But the word may be merely one of the numerous popular formations of no definite elements, so freely made in the Elizabethan period" [Century Dictionary].