also bushwah, 1906, U.S. slang, perhaps originally among students, euphemistic for bullshit (n.).
Entries linking to bushwa
bullshit n.
also bull shit, "eloquent and insincere rhetoric," 1914, American English slang; see bull (n.1) + shit (n.), probably because it smells. But bull in the sense of "trivial or false statements" (1914), which usually is associated with this, might be a continuation of Middle English bull "false talk, fraud" (see bull (n.3)).