Green’s Dictionary of Slang

sucky-sucky n.

fellatio.

1975		J. Wambaugh Choirboys (1976) 226: She says sucky fucky and gets cute about the price.
1984		B.J. Friedman Let’s Hear it for a Beautiful Guy 53: ‘Fucky, fucky,’ the older one whispered in his left ear; ‘Sucky, sucky,’ her sister said in his other ear; and for fifty dollars he was off to the races.
1991		C. Hiaasen Native Tongue 271: She’s more comfortable with the old sucky-fucky.
1998		M. Walters Echo 140: You like sucky-sucky? Sounds good, eh, sweeties?
2003		E. Landers Smooth 445: ‘Sucky-sucky?’ The woman was versatile, you had to give her that. ‘No! No! No sucky-sucky. No ficky-fick. Jesus!’.