Bullshit

google

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early 20th century: from bull3 + shit.

wiktionary

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bull +‎  shit. In use since 1914. 

etymonline

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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)).

bullshit (v.)

by 1942, from bullshit (n.). Related: Bullshitted; bullshitting.