When you stick your finger in someone else's fist repeatedly.

Anatidaephobia is defined as a pervasive, irrational fear that one is being watched by a duck. The anatidaephobic individual fears that no matter where they are or what they are doing, a duck watches.

Anatidaephobia is derived from the Greek word "anatidae", meaning ducks, geese or swans and "phobos" meaning fear.

The act of putting a condom (used or not) on your fingers as many as you please or even your whole fist and have your partner create a hole with their hand and you then insert your fingers or fist into the hole and move in out repeatedly multiple times

when a girl or guy sticks his or her finger(s) up a girl. Or when a girl uses her fingers to "rub" her genitals for sexual pleasure.