Green’s Dictionary of Slang

deep six v.

[naut. use deep six, to throw overboard; ult. SE phr. six feet under, dead]

1. (orig. US) to get rid of, to abandon.

[US]Boy’s Life Apr. 14/4: ‘Throw them overboard!’ roared Mr. Perkins. So, sadly, Muggy gave them the deep six .
[US]P. Kendall Dict. Service Sl. n.p.: give it the deep six . . . toss overboard. [Ibid.] deep six . . . bury something.
[US]Swinging Syllables n.p.: Deep-six: Dispose of, get rid of.
[US]L. Bruce How to Talk Dirty 39: That was the prevailing climate: If it’s dirty, paint it; if it’s broken, ‘deep-six’ it.
[US]E. Torres After Hours 7: This guy use, this guy deep-six.
[US]D. Woodrell Muscle for the Wing 155: The next day she deep-sixed education and called her old friend Sandy.
[UK]Guardian Guide 8–14 Jan. 4: The decision to deep-six the village’s name was widely viewed as a slap in the face of the town’s long-term residents.

2. (orig. US) to ruin, to destroy.

[UK]P. Theroux London Embassy 114: If the British knew the kind of information we had on them in this thing, they’d deep-six every one of us.
[US](con. c.1970) G. Hasford Phantom Blooper 196: we are going to deep-six you for collaborating with the enemy in time of war.
[UK]Indep. Rev. 1 Oct. 5: Been on my uppers ever since I was deep-sixed by the bank for speculating with their assets.
[US](con. 1973) C. Stella Johnny Porno 206: Chasing this dopey film is policy [...] Deep Throat is supposed to be deep-sixed.

3. (US) to kill, to die.

[UK](con. 1943) A. Myrer Big War 170: Should of let her deep-six herself.
[US]B. Rodgers Queens’ Vernacular 158: If one has been killed, he has been deep sixed.
[UK]J. Morton Lowspeak 48: To deep six – to kill.
[US]T. Piccirilli Fever Kill 133: His business rivals wound up deep-sixed and knife-juked.

4. (US campus) to expel from a college.

[US](con. 1964) G. Wolff Duke of Deception (1990) 235: Only a couple of friends took gas, were deep-sixed from Princeton prematurely and against their wishes.

5. (US campus) to finish a six-pack of beer.

[US]Eble Campus Sl. Fall 3: deep six – to put an end to something, particularly to drink up a six-pack of beer.