Green’s Dictionary of Slang

lug n.2

[SE lug v., to drag, to haul. Such a heavyweight would need to be dragged along, mentally or physically. Note Scot. luggie, awkward, sluggish; mid 16C SE lug, something heavy and clumsy may be only coincidental]
(orig. US)

1. a large, stupid man.

[US]Daily Trib. (Bismarck, N.D.) 23 Oct. 4/1: Those people who [...] haunt stage doors [...] are ‘gillies,’ ‘gills,’ ‘guys,’ ‘chappies,’ ‘mashers,’ ‘chumps,’ ‘lunkheads’ and ‘lugs.’.
[US]E.H. Lavine Third Degree (1931) 48: If you don’t tell me where Jim the Lug is, I’ll kick your brains all over the room.
Ottowa Citizen (Ontario) 11 June 19/1: He’s talking to a muddle-headed lug named Fowler.
[US]S. Longstreet Decade 317: Don’t highball any hideout for this lug. He’s hot, this lamster.
[US]J. Thompson Swell-Looking Babe 57: Hey, you lug! Get out of the lady’s way.
[US]Atlantic Monthly July 108: Michael Meyer as Brenda’s jock brother, a big, gregarious, simple-minded, good-hearted lug who has exactly the right moves of the athlete.
[Can]R. Caron Go-Boy! 197: One of my duties would be refereeing fights between these two lugs.
[US]S. King It (1987) 456: A big lug with a broken nose named Romeo Dupree.
[UK]A. Higgins Donkey’s Years 39: You great lug you.
[US]P. Roth Human Stain 216: This brute-sized, opaque, pony-tailed lug without any desire ever to speak.
[US]E. Weiner Drop Dead, My Lovely (2005) 52: The lug was Pakistani, or Indian, one of those subcontinent birds.
[US]‘Jack Tunney’ Split Decision [ebook] If some big lug hit me with cannon balls for fists, I was sunk.

2. a lout, a sponger.

[US] ‘Und. “Lingo” Brought Up-to-Date’ L.A. Times 8 Nov. K3: LUG: A stupid fellow; a hanger-on.

3. a general term of abuse.

[US]J. Gray ‘The Nudist Gym Death Riddle’ in Vice Squad Detective [Internet] These lugs aren’t just interested in working off surplus poundage.
[US]J.H. O’Hara Pal Joey 15: Those lugs in the band would begin to kid me about it.
[US]F. Brown Fabulous Clipjoint (1949) 114: Who were the other lugs who were with Reynolds [...] ?
[US]R. Prather Scrambled Yeggs 52: I’d already had enough of this lug’s glares and growls.
[Can]R. Caron Go-Boy! 19: Goddam you lugs!
[US]J. Stahl Permanent Midnight 75: It was a complaint any teenage lug in the world could have understood.
[Ire]P. McCabe Emerald Germs of Ireland 360: The dirty lug!

4. a person, irrespective of character.

[US]Mad mag. Apr.–May 12: Sheldon was a sswell [sic] lug! But he was so unromantic!

In compounds

lughead (n.) [-head sfx (1)]

(US) a stupid person.

Michigan Technic (U. Michigan Coll. Engineering) 56-7 151: Urbane W. Hird, better known as Tim, Thundering Hird, U. W., or the Lughead, steps into the spotlight.
G. Wilhelm Never Let Me Go 103: There I sat, sleeping through the whole thing like a damned lughead.
[US]W. Guthrie Seeds of Man (1995) 223: Whatta deed he do, theesa beega lug head?
S. Heym Eyes of Reason 327: He had let himself get rattled by a lughead of a General.
L. Meyer Customer Is Always 59: ‘Shah . . . where are you?’ the boss would plead, and Shah would laugh quietly and blend into the books and taunt inaudibly, ‘Find me, you lughead!’.
J. Roberts Education of Oversoul Seven 68: That lughead just dumped the entire contents of Lydia's shell collection on the floor!
S.R. Christian Alive 111: Your first impulse is to get some revenge, if only to yell ‘You stupid lughead’.
[US]Spin Apr. 164/2: Tad is a really smart guy, he's really articulate, and they marketed him as this big, brooding sort of lughead.
[US]NSWCorp 3 Apr. [Internet] How did Harvard let a deranged lughead like the author of this piece into its esteemed law school?

In phrases

put the lug on (v.) (also drop the lug on)

1. to beg; to demand money with menaces, to extort, to blackmail .

[US]V.W. Saul ‘Vocab. of Bums’ in AS IV:5 343: Put the lug on—To beg from someone.
[US]D. Runyon ‘Hold ’Em, Yale!’ in Runyon on Broadway (1954) 148: She will next be trying to put the lug on me for a ducket.
[US]Topeka Journal 26 Mar. 8: Shakedowns in Topeka are known to have ranged from $20 to $50 monthly, depending on the amount of illegal business done by the individuals on whom the lug was put.
[US]Charles Carson in Author and Journalist Nov. n.p.: How’s about droppin’ the lug on you for thirty-five hundred? [W&F].

2. (US) to beat up, to use violence against.

[US]Hecht & Fowler Great Magoo 69: You take that back or I’ll put the lug on you.
[US]A.J. Pollock Und. Speaks n.p.: Put the lug on, to beat up a racketeer.
[US]Goldin et al. DAUL 170/2: Put the lug on. To remove forcibly with the aid of strong-arm accomplices an irate victim from the scene of the swindle, as at a carnival.