Green’s Dictionary of Slang

1. rubbish, nonsense [abbr. bullshit n. (1)].

1919		W.H. Downing Digger Dialects 14: bullsh (n.) — (1) Insincerity; (2) an incorrect or insincere thing; (3) flattery; (4) praise.
1920		Argus (Melbourne) 17 Jan. 6/6: Mr. Arthur Adams was agonising over a rhyme for ‘bullsh’.
1938		X. Herbert Capricornia (1939) 347: This talk of invasion by the Japs is all plain bulsh.
c.1943		S .J. Baker Aus. Vulgarisms [t/s] 7: bullsh: Nonsense, humbug. Short for bullshit.
1951		(con. 1941) E. Lambert Twenty Thousand Thieves 13: I just couldn’t stand there any longer and listen to that bullsh.
1959		D. Hewett Bobbin Up (1961) 55: Who’s been fillin’ you up with all that bulsh. Dick I s’pose?
1961		K. Cook Wake in Fright [ebook] ‘Have another?’ ‘Oh… I don’t really like to… I…’ ‘Ah bulsh, you can buy me a few next time you see me.
1963		A.E. Farrell Vengeance 123: ‘Bullsh!’ ejaculated Bob.
1970		(con. 1941) R. Beilby No Medals for Aphrodite 158: I wouldn’t know about all that bullsh.
1978		Edwards & Reed [bk title] Bullsh: or That Bloody Cow.
1985		B. Robinson Aussie Bull x: Some timid and unnecessarily polite people refer to it rather gently as ‘Bullsh’ or ‘Bull Dust’.
1988		McGill Dict. of Kiwi Sl. 22/2: bullsh nonsense; short for ‘bullshit’.
2003		McGill Reed Dict. of N.Z. Sl. [as cit. 1988].

2. (also bullshartist) a braggart, a liar [abbr. bullshitter n. (1)].

1938		X. Herbert Capricornia (1939) 446: More bettel you nick off yourself, you big fella bulsh — gwan — hoppit!
1946		R. Rivett Behind Bamboo 395/2: Bullshartist, great talker of nonsense, a garrulous person.