The word duck is an abbreviation of the term 'Silent Duck' which refers to the shape made by the hand during fisting, or initiation into fisting. Silent Duck
And so the term cheeky duck refers to slyly slipping a silent duck in during sex, aimed to catch the receiver off guard.
Slang for smegma: the secretion of a sebaceous gland
specifically : the cheesy sebaceous matter that collects between the glans penis and the foreskin or around the clitoris and labia minora
After going three days without a bath, Charlie had a buildup of duck cheese on the head of his penis.
It is said of the situation where a person has the bad luck to make contact with his testicles against an undefined surface or object, intentioned or not.
Given the nature of the word, it is more appropriate to design cases where the interaction is made with a moving object, for example, a ball.
Although it is extremely painful for the victim, it tends to be considerably funny to people who witness it.
Today in the baseball game the pitcher took a nutshot; the baseball hit him in the nuts.
Man, I just watched the funniest nutshot video ever.