Green’s Dictionary of Slang

hack v.1

1. (US campus) to socialize, to waste time, to idle.

[US]Stag Party n.p.: It is said we are all good at ‘hacking,’ / Dancing, drinking, hugging, and smacking .
[US]N.Y. Times 18 Aug. I 72: Much more time is spent hanging around or ‘hacking,’ as the young people call it [HDAS].

2. (US) to neck, to kiss, to engage in sexual activity.

[US] ‘Whitman College Sl.’ in AS XVIII:2 Apr. 154/1: hacking. Necking, petting, spooning, courting, depending on how old you are.
[US]R. Moore Green Berets 132: The men loved Sergeant Hanh, who took them to the local whorehouse and let them take pictures of him hacking.

In phrases

hack around (v.)

1. (US campus) to socialize, to fool about.

[US]DN V 209: To hack ramble around.
[US]M. Shulman Rally Round the Flag, Boys! (1959) 43: She was always hacking around and yocking up a storm.
[US]N.Y. Times Mag. 4 Apr. 99: ‘Hacking around’ (which can be roughly translated as ‘fooling around’ or ‘doing nothing’) is a favorite teen-age pastime.
[US](con. 1950s) H. Junker ‘The Fifties’ in Eisen Age of Rock 2 (1970) 101: If you weren’t grounded, you could [...] hack, screw, mess around.
[Can]Totally True Diaries of an Eighties Roller Queen 🌐 16 Aug. My dad came at 5:30 to pick me up and then I just hacked around with Jamie and Bob, Laura and Steve and Tracey until my parents told me to come in.

2. (US) to joke, to tease.

[US]G.V. Higgins Cogan’s Trade (1975) 65: ‘Oh for Christ sake [...] I was just hacking around.’ ‘Not on that [...] Ginny, Ginny’s sacred to me.’.

3. (US, also hack off) to waste time.

[US]Baker et al. CUSS 132: Hack around [...] Hack off Waste time, not study.
[US]G.V. Higgins Friends of Eddie Coyle 30: I got to stop hacking around.
[US]G.V. Higgins Patriot Game (1985) 98: I was afraid I’d screw everything up if I marched in and started hacking around with thing thing.