Green’s Dictionary of Slang

1. something that causes annoyance or is difficult or hard to deal with.

1733		Laugh and Be Fat 25: No sooner was he admitted into his noisy Habitation, but he found his Teaser so full charged with ill Language, that she let fly a Vally of Rogues and Rascal at him.
1759		Franklin Essays & Tracts (1840) III 380: On the moeeow he plyed them with another teaser .
1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc. 170: Teazer [...] a talking fellow who haunts another.
1832		Egan Bk of Sports 28: Perkins is very likely to prove a teazer to most of the light weights.
1842		Egan ‘Jack Flashman’ in Farmer Musa Pedestris (1896) 141: Jack long was on the town, a teazer; / A spicy blade for wedge or sneezer; / Could turn his fives to anything / Nap a reader, or filch a ring.
1845		Bell’s Life in Sydney 6 Sept. 4/2: But quickly on his pins again he meditates a teaser / Bungs up the eye of Bungaree and clareted his sneezer.
1857		G. Lawrence Guy Livingstone 84: The third is a teaser – an ugly black bullfinch with a ditch on the landing side.
1885		Bulletin (Sydney) 8 Aug. 13/3: We consider that, in quantity, the ‘native’ [wine] predominated over the ‘foreign,’ though one of the stewards [...] handed us a bottle of imported hock, which was a ‘teazer.’ [Ibid.] 15 Aug. 14/1: It says much for the man’s power of concentrating his mind on any subject that he successfully kept his three years’ terms at the Middle Temple, and passed examinations which are now ‘teasers,’ and not the mere matter of form of 50 years back.
1937		J. Curtis There Ain’t No Justice 153: I thought from all the hoohah you were making that you were going to set me a regular teaser.

2. a blow with the fist.

1824		Annals of Sporting 1 Mar. 200/1: [He] put in such a teazer on Goldie’s smeller as brought away the claret in copious streams.
1828		Sussex Advertiser 14 Apr. 4/3: If Brown only gives you one of his teazers, you’ll ‘hop the twig’.
1834		Ely’s Hawk & Buzzard (NY) Sept. 6 n.p.: Sam popped in a left-handed teazer.
1843		Satirist & Sporting Chron. (Sydney) 4 Feb. 2/2: Baily received such a teazer in his left eye, that the claret not only spun out, but his nob was like a spinning top in full motion.
1849		Sam Sly 17 Feb. 3/1: He advises Jemmy Sh—w not to drink so much heavy wet [...] Reform, or you shall have a teaser.
1855		(con. 1837) Fights for the Championship 358: Lazarus stopped a left-handed teazer.

3. the male genitals and pubic hair.

1881

Loves of Venus 44: ‘Did you ever see such a teazer as the old fellow’s got, and as grey as a badger.