Green’s Dictionary of Slang

1. (also break down, break it on down) to explain, to put the listener right.

1928		Tailor and Cutter 29 Nov. in DSUE (1984).
1959		L. Lariar Death Is Confidential n.p.: ‘I’m listening,’ he said, ‘Break it down.’.
1966		B. Jackson Get Your Ass in the Water (1974) 127: ‘If you know what to do, / you can spend this night and the rest of them too.’ / Now fellas, I have to admit I was a little green, / so I tell her to break it on down and tell me what she mean.
1975		E. Torres Carlito’s Way 37: I break it all down for the lawyer.
1985		N. Pileggi Wiseguy (2001) 183: Then Fran broke down about the robbery.
1998		Big L ‘Ebonics’ 🎵 Yo, pay attention / And listen real closely how I break this slang shit down.
2002		50 Cent ‘Wanksta’ 🎵 Break it down / I got a lot of livin’ to do ’fore I die.

2. (Aus.) to give in, to desist; to act reasonably.

1934		Courier Mail (Brisbane) 18 Apr. 9/5: The defendant, when interviewed in connection with the charge, said: ‘Break it down. I know nothing about that. I have turned that game up long ago, you should know that’.
1941		Howard ‘Heat’ in Mann Coast to Coast 127: Ah, break it down, feller.
1951		Cusack & James Come in Spinner (1960) 264: Break it down, Peg, you’ve turned into a regular prickly pear since I’ve been away.
1965		D. Martin Hero of Too 324: ‘Break it down!’ ‘Who said that—you, George? Break it down, eh?’.
1971		F.J. Hardy Outcasts of Foolgarah (1975) 77: Break it down, Hambone. Buzz orf!
1984		W. Ammon et al. Working Lives 62: ‘Ah, break it down will you,’ I snorted, feeling silly.
1996		Penguin Bk of More Aus. Jokes 412: ‘Tell her Highness how much you can lift, Dave.’ [...] ‘About a fuckin’ ton.’ ‘Break it down!’ whispered the shocked official.

3. to speak unrestrainedly.

1989

Eble Campus Sl. Sept. 1: break it down – be blunt in expressing oneself: Let me break it down to you – your breath stinks!