Green’s Dictionary of Slang

dipper n.¹

a Baptist; an Anabaptist.

1640		‘A Romish Priest’ in Wardroper (1969) 151: A world of bastards he begot / Which to religion are a blot: / Dippers, Seekers, Shakers, Quakers / And all other truth-forsakers.
1654		Mercurius Fumigosus 19 4–11 Oct. 170: A zealous Dipper [...] placed his Bed right against his Neighbors Bed, so that there was nothing but a thin loom Wall and a Painted Cloath between one bed and the other, through which he made a hole bigg enough to put in his Arm, and so by drawing up the painted-cloath, could at his pleasure handle his Sisters flesh.
c.1698		B.E. Dict. Canting Crew.
1725		New Canting Dict.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Dippers, anabaptists.
1796		J. Morse Amer. Geography I 281: The English word that conveys the proper meaning of Tunkers is Sops or Dippers [DA].
1809		G. Andrewes Dict. Sl. and Cant.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1835		G. Kent Modern Flash Dict.
1849		Morn. Post (London) 19 Oct. 7/4: Walis gave rise to a sect [...] of Anabaptists, who received the name of Dompellers, i.e. Dippers from their plunging into the water.
1867		W.H. Dixon New America II 184: The Tunkers [...] profess Baptist tenets; and the word ‘tunker’ meaning to dip a crumb into gravy, a sop into wine, they are described by those who use it, in a very poor joke, as dippers and sops. [...] We English style them Dunkers, by mistake [DA].
1869		Democratic Press (Ravenna, OH) 27 May 1/7: A refutation accordingly appears, entitled ‘The Dipper Dipt, or the Anabaptists Ducked and Plunged over Head and Ears’.
1900		Bulletin (Sydney) 6 Oct. 12/4: Nowadays and hereabouts the Dipping denomination’s handsomest and most actor-like parson is Baptiser-in-chief.
1953		H. Tracy Mind You, I’ve Said Nothing (1961) 112: The pity is that they are divided into five groups, Church of Ireland, Methodists, Baptists, Plymouth Brethren, and Cooneyites, or Dippers.

SE in slang uses

In phrases

get one’s dipper wet (v.)

(US) of a man, to have sexual intercourse.

1980

W. Sherman Times Square 127: I didn’t see you getting your dipper wet.

In exclamations

in one’s dipper! [? sheep dip; but note in one’s ballocks under ballocks n.]

(N.Z.) a general excl. of rejection, dismissal.

1938		Press (Canterbury) 2 Apr. 18: The most staid will sometimes catch up a meaningless phrase like ‘in your dipper’ [...] or ‘sez you’.
1988		McGill Dict. of Kiwi Sl. 37/1: dipper, phr. in your dipper! expression of defiance between world wars; possibly ref. to sheep dip.
2003		McGill Reed Dict. of N.Z. Sl. [as cit. 1988].