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finger-fuck

American  
[fing-ger-fuhk] / ˈfɪŋ gərˌfʌk /
Or finger fuck,

verb (used with or without object)

Slang: Vulgar.
  1. to stimulate (the vagina or anus) for sexual gratification by penetration with one or more fingers.


Etymology

Origin of finger-fuck

First recorded in 1680–90; finger ( def. ) + fuck ( def. )