pinky dinky is a small penis or "dinky" as some girls will call it, usually the girl will look at her own pinky finger or her thumb and she will laugh if your dick is the same size or smaller
Tiffanie looked down and saw that his dick was even smaller than her thumb. She almost choked with laughter but tried to remain calm. She quickly realized her thumb was bigger than Travis' pinky dinky. She started to laugh, but needed a ride home so she caught herself. The following week, every girl in high school would not date Travis unless they were interested in small penises.
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.