Green’s Dictionary of Slang

1. eating.

1840		Comic Almanack Feb. 214: They put you to trough very respectably in this same shop: ask, and have, that’s the ticket.
1900		‘Doss Chiderdoss’ ‘A Dangerous Dad’ Sporting Times 3 Feb. 1/4: ’E’s a right to ’is share of the nosebag and trough.

2. the place at which one eats.

1901		‘Hugh McHugh’ John Henry 56: I bumped into Buid the other evening and I led him to a trough.
1911		G. Bronson-Howard Enemy to Society 76: I felt like saying ‘Let’s all go to the trough,’ when dinner was announced.
1920		Ade Hand-made Fables 129: What is now called Service consisted of cleaning up the Trough and going back for another Load.
1939		Wodehouse Uncle Fred in the Springtime 147: ‘Dinner. Let us be going down. We do not want to be late for the trough’.
1944		C.S. Montanye ‘Shoulder Straps’ in Thrilling Detective Feb. 🌐 Figured where you’d like to feed, baby? You pick the trough.
1954		Wodehouse Jeeves and the Feudal Spirit 90: When the gong went I had to leg it to the trough.
1960		Wodehouse Jeeves in the Offing 32: Only Bobbie was present when we arrived at the trough.
1983		A. Payne ‘Willesden Suite’ Minder [TV script] 71: The Rotarians at the trough.

3. (US) the female genitals, thus slopping the trough, performing ciunnilingus.

2007

‘Bootscooter’ August Moone 7:56 🌐 ‘Eatin’ pussy. Sloppin’ the trough. Carpet bumping. Eating at the Y. Clam diving’.