Green’s Dictionary of Slang

1. to take the entire length of the penis into one’s mouth, and thus down one’s throat, during fellatio, also as adv. taking the penis down one’s throat, and n. deep-throater.

c.1972		‘C. Howard’ Team Hunk 25: You just deep throat it a couple...couple times and I’ll rinse down your tonsils [Simes:DLSS].
1979		in Playboy Aug. 52: She proceeded to deep-throat me.
1979		‘C. Caldwell’ Horny Studs’ Ranch 115: [H]e was hung big [...] he’d had plenty of experienced cocksuckers choke on his meat!—but Johnny was taking him deep-throat the first time out! [Simes:DLSS].
1991		C. Hiaasen Native Tongue 39: Students [...] were instead exposed to a mattress-level montage of Latin porn star Pina Kolada deepthroating a semi-pro soccer team.
1998		D. Laurents Young & Hung 4: [deep] [no text] [Simes:DLSS].
1998		Beckford & Dax D.O.C. Lust Letters 24 mar. 59: I’m busy again, deep-throating him, changing positions, using hands, mouth, tongue [Simes:DLSS].
1999		‘Master Pimp’ Pimp’s Rap 54: As she slowly deep throated my rod, her sexy eyes told me I was going to love every minute of it.
2004		N. Kelley ‘The Code’ in Brooklyn Noir 191: Knee-deep into deep-throating Dominique, Code could feel his own backdoor being prepared for a rear-entry maneuver.
2005		L. Theroux Call of the Weird (2006) 61: I’m not into rough sex. I don’t mind you deepthroating me but treat me right.
2005		SX National (Sydney) Jan. 41/1: [personal advert] Two horny guys [...] good deep throaters, if you want your cock sucked [Simes:DLSS].
2019		D. Winslow Border [ebook] He presses her head down. ‘Deep throat me’.

2. in a non-sexual or semi-sexual sense, e.g. to suck suggestively on a straw.

1999

‘Master Pimp’ Pimp’s Rap 48: She crossed her big pretty legs and enticed me by deep throating the straw in her drink giving me the impression that she knew how to use her mouth for more than just to talk.