Barrère, Albert; Leland, Charles Godfrey(1889)A Dictionary of Slang, Jargon & Cant, volume 1, page 54
Farmer, John Stephen(1890)Slang and Its Analogues, volume 1, page 81
Etymology
From autem(“church”) + dip(“The action of dipping or plunging for a moment into a liquid.”) +-er, referencing the practice of baptism by being dipped in water.