Green’s Dictionary of Slang

a fist-fight; in weak use, an argument (see cite 2020).

1896		F. Hutcheson Barkeep Stories 74: [I]n about a secon’ I’m in a mix-up with him an t’irty of his fren’s.
1905		H. Green Actors’ Boarding House (1906) 31: The peach’s husband was a handy lad in a mixup.
1908		Sun (Kalgoorlie, WA) 6 Sept. 4/8: You could see from the very first ‘mix-up’ , / He had him as wet as a shag.
1910		H. Hapgood Types from City Streets 322: I’ve been in many a mix-up that resulted in blood.
1919		E. Dyson ‘Mickie Mollynoo’ in ‘Hello, Soldier!’ 39: A shine John Hop is Mollynoo. A mix-up / with the push Is all his joy.
1920		B. Cronin Timber Wolves 223: Well, that certainly was one hell of a mix-up.
1924		G. Henderson Keys to Crookdom 411: Mix-up. A fight, a fracas.
1930		J. Lait Gangster Girl 154: Unaware of what the fight was about or who was fighting — sailors, stevedores and bums — unable to resist a good scrap, jumped into the mixup.
1936		C. Drew ‘Nosey’ in Bulletin 24 June 28/2: ‘I ain’t a world-beater, of course, but I can hold me own in a general mix-up’.
1942		S. Philips Big Spring 169: He seemed to have got into a mix-up with his wife.
1949		Monteleone Criminal Sl. (rev. edn).
2020		G. Krauze What They Was 163: If you get involved in someone else’s mixup [...] it will sinattly spark off a next beef ting.