Green’s Dictionary of Slang

1. to drink a full can of beer in a single swallow, esp. when a hole has been poked through the bottom.

1986		Dly Press(Newport News, VA) 10 Nov. 3/4: They get up from the table to ‘shotgun’ a beer using a ‘beer bong’, a six-foot tube attached to a funnel that allows the user to drink an entire beer in one swallow.
1994		Sth Florida Sun Sentinel 19 Jan. 6E: If someone says something like that they’re ostracized and forced to shitgun a beer.
1995		Eble Campus Sl. Apr. 9: shotgun – slam an alcoholic beverage on the bar and then drink it quickly: ‘Shotgun that beer!’ Punch a hole in the bottom of a beer can and drink it in one swallow.
2003		T. Dorsey Stingray Shuffle 121: [...] simultaneously trying to shotgun a beer and fire up a six-foot Cambodian peace pipe.
2015		Tallahassee Democrat (FL) 31 May 3C/5: He [...] celebrated a double up in Durham by [...] shotgunning a beer.

2. (drugs) to blow cannabis smoke into someone else’s mouth by reversing the cigarette inside one’s own mouth and blowing; the other person places their open lips near the stream of smoke and inhales for as long as they can [shotgun n.² (2)].

1993		G.P. Pelecanos Nick’s Trip 131: The bearman had lit the joint and was stooping low as he shotgunned Ken.
2001		ONDCP Street Terms 19: Shotgun — Inhaling marijuana smoke forced into one’s mouth by another’s exhaling.
2012		G. Pelecanos (con. 1972) What It Was 59: She produced a number and fired it up [...] Grady Page joined them for a minute. He and Strange shotgunned each other.
2015		P. Beatty Sellout (2016) 64: Shotgun weed smoke into her pursed and needy lips.

3. (Aus.) to pressurize, to persuade.

2009

P. Temple Truth 19: In high school he had been in a play, shotgunned by a spunky teacher.

4. (US) to throw hard.

2012

J. Duke ‘Bastards of Apathy’ in ThugLit Sept./Oct. [ebook] [H]e shotgunned the egg so hard at the rusted metal pedestal [...] he felt the air snap.