Green’s Dictionary of Slang

1. an overweight person; often used as a nickname for such a person; thus a lazy, good-for-nothing person.

1935		J. Conroy World to Win 212: Hey, lardass, don’t let that popgun go off in ya hand.
1953		L. Uris Battle Cry (1964) 41: I want the lard asses to my left. [Ibid.] 56: Hey, lard, you sick?
1962		(con. 1930s) H. Simmons Man Walking On Eggshells 29: Coach Blakey invited me to the tryouts, not ole lard ass.
1977		J. Sayles Union Dues (1978) 38: Old lard-ass shouldn’t be much trouble we put the scare in him though.
1988		(con. 1940s) C. Bram Hold Tight (1990) 227: Draft-dodging lard-ass.
1989		H. Rawson Dict. of Invective (1991) 232: lard. Fat, in various combinations, e.g., lard ass, lardball, lard bucket, and tub of lard, all referring to a grossly overweight person, and lardhead, to a dumb one.
1990		S. Morgan Homeboy 119: They’re gonna have to build you a custom seat for the chamber, lard-ass.
2005		Mad mag. May 45: A [...] white, middle-aged, bloated, funk-free, lard-ass.
2007		S. Maloney Sucked In Fuck that lard-arse, he had it coming.
2012		T. Pluck ‘Summer of Blind Joe Death’ in Life During Wartime (2018) 182: ‘Hush, lard ass’.

2. a fat posterior.

1964		H. Selby Jr Last Exit to Brooklyn 88: Her big lardass was wrigglin and we were pissin in our pants.
1979		T. Alibrandi Killshot 72: You can take your report and cram it up your lard ass.
2000		F. Kellerman Stalker (2001) 30: ‘I no have lardo ass!’ Estelle screamed. ‘Your whore have lardo ass, beeg, fat ass!’.
2015		G. Disher Heat [ebook] Julie grunted, shifted her lard-arse to the front edge of the seat cushion.