Green’s Dictionary of Slang

1. (US) a serious mistake; esp. in phr. pull a boner

1912		Amer. Mag. June 200/1: Boner — a stupid play; a blunder in the science of the game .
1916		Day Book (Chicago) 20 July 10/2: He didn’t look around the field. It was a cold boner.
1929		W. Winchell On Broadway 19 Sept. [synd. col.] When the inexperienced badmen discovered their boner two days later, they [...] wrote him a letter of apology.
1930		J. Lait Put on the Spot 62: If it was a boner, let’s pick the bones out of it.
1938		W. Winchell ‘On Broadway’ 2 Dec. [synd. col.] How did I make that boner about Woollcott’s ‘My Little Boy’ being in his Second Reader when it’s in his First?
1942		W. Winchell ‘On Broadway’ 14 Apr. [synd. col.] What the infallible Pegler didn’t add was that the humiliating boner appeared in [...] his own sheet.
1952		Lait & Mortimer USA Confidential 9: The chiselers, with no independent means of their own, all made the same boner.
1969		‘Iceberg Slim’ Pimp 187: Don’t repeat your boner.
1971		Wodehouse Much Obliged, Jeeves 124: In signing on the dotted line with Florence I had made the boner of a lifetime.
1996		H. Roth From Bondage 183: Boy, that was a boner.

2. (US campus) a difficult examination.

1967–8

in Baker et al. CUSS.