Green’s Dictionary of Slang

1. (US Und.) an unpleasant or undesired result, repercussions.

1892		Daily News 30 June 5/5: It is [...] quite a boomerang business. Tories built the fort in anticipation of the battle of 1880, and to-day the Liberals hold it.
1909		J. Ware Passing Eng. of the Victorian Era 42/2: Boomerang (American, 1882). A vain folly, the consequence of which returns upon the perpetrator.
1938		J.E. O’Donnell ‘Overcoat Bennie’ in Mss. from the Federal Writers’ Project 🌐 He bought the necklace when Bennie assured him that there was no chance of a boomerang. How could there be a boomerang, Bennie said, when he, himself, had smuggled it into the U. S. A. from Russia?
1967		A. Niederhogger Behind the Shield 181: In talks on the complex subject of human relations there is always the possibility of a boomerang effect.
1979		T. Rhone Old Story Time II iii: And what happens to your mother? You goin’ to leave her wide open for the boomerang?

2. (US teen) a girl’s unwanted admirer who refuses to abandon their pursuit.

1944

N. Pepper in Baltimore Sun (MD) 16 Jan. A2/2: Boomerang — A drippy boy that you can’t shake off.

3. (Aus.) something, esp. a book, that one wishes to have returned.

1955

N. Pulliam I Travelled a Lonely Land (1957) 230/2: boomerang – [...] an article has been lent only, is to be returned.