Green’s Dictionary of Slang

(US) a euph. for bullshit n. (1); also as excl.

1928		C. McKay Home to Harlem 48: ‘I won’t scab on nobody, not even the orneriest crackers,’ he said. ‘Bull Durham!’ cried Zeddy.
1930		G. Milburn ‘Harvest Land’ in Hobo’s Hornbook 102: ‘Bull Durham’ will not buy our brawn – / You’re out of luck – poor Farmer John.