Green’s Dictionary of Slang

1. to leave work, i.e. to punch the timeclock.

1986		L. Heinemann Paco’s Story (1987) 91: Job’s a job, man. You do it and punch out and go home.
1991		B. Hamper Rivethead (1992) 61: I would give my ID badge to Dale so that he could punch me out at quitting time.
1993		R. Shell Iced 108: We would punch out [...] and she and I would wind up at Ken’s.
2004		E. Weiner Drop Dead, My Lovely (2005) 6: They can punch out and go home.

2. (US) to beat up, to assault with the fists.

1947		J.W. Arnold ‘The Lang. of Delinquent Boys’ in AS XXII:2 Apr. 122: Punch out. (1) To hit a boy.
1967		L. Bruce Essential Lenny Bruce 229: A portion of the audience would want to punch me out.
1978		R. Caron Go-Boy! 45: Sergeant Tracy [...] never failed to capture at least one would-be escaper, punch him out too!
1986		R. Campbell In La-La Land We Trust (1999) 155: The next thing you know, she wants to cop a sneak [...] and then you got to punch her out, shut her up, ruin her kisser.
1991		B. Hamper Rivethead (1992) 57: By night’s end you’d be totally gassed and ornery enough to punch out your own grandmother.
2001		‘Gunga Dick’ ‘Jesse’ 🌐 We stopped to watch [...] the ubiquitous mime who mimicked people as they walked past. I’m always surprised when no one punches these guys out.
2003		McGill Reed Dict. of N.Z. Sl.
2005		L. Redhead Rubdown [ebook] ‘What happened to your face?’ ‘Suzy was pissed and punched me out’.

3. (US campus) to fail in one’s studies.

1967		A. Baraka Tales (1969) 13: You better start thinking about him [i.e. a professor] or you’ll punch right out.
1974		Eble Campus Sl. Oct. 3: punch out – to fail out of school; to make all F’s.

4. in fig. use, to reject, to turn against.

1977

C. McFadden Serial 60: Bill said he ‘punched out at raw fish’.

5. to crash.

1987

C. Hiaasen Double Whammy (1990) 31: A young man [...] flipped his rig doing about sixty on the lake. Hit a cypress knee and punched out.

6. to die.

2006

F.X. Toole Pound for Pound 236: Simplify it [i.e. a document] to go into effect at the time I punch out.