Green’s Dictionary of Slang

break it off in v.

also stick it in and break it off
[the image is of some form of knife]

(US) to treat or hurt badly.

[US]O. Wister Texas Vocab. in Wister Owen Wister Out West (1958) 159: To break it off in a person to get the better, to outdo.
[US]J.C. Ruppenthal ‘A Word-List From Kansas’ in DN IV:ii 103: break off in, v. phr. To revenge (something) on (one). ‘The first chance he gets he will break it off in you.’.
[US]‘Paul Cain’ Fast One (1936) 209: Fenner hasn’t played ball - I can stick it in him and break it off.
[US]R. Chandler Lady in the Lake (1952) 13: He would have been tickled pink to stick it into me and break it off.
[US]Goldin et al. DAUL 211/1: Stick it in and break it off. (P) To exact the last ounce of vengeance.
N. Bush Hate Merchant 8: Give you apricots, a free ride, flatter you a little so you’d listen and then — socko, stick it in and break it off.
J. Weeks Some Trust in Chariots 220: The right way is to learn everything you can about their goddamned company and then stick it in and break it off some day.
W. Burroughs My Education 112: So here you are, and here he is, and you shouldn’t be here at all, which is bad enough, but to really stick it in and break it off, you have to pick him up.
J.M. Gambee Til Dead Do Us Part 106: There’s an IAD brass asshole whose [sic] had it in for Calvin for a long time and he’s looking at this as his chance to stick it in and break it off.