If a phrase that originated on the basketball court. It is in reference to referees or players on the streetball court calling soft fouls.
In the eyes of some, soft fouls being called only slow the game and detract from the contest and beleive that unless the contact is significant there is no point in calling the foul. Hence, No harm, no foul.
Example A
Player A: 'you fouled me'
Player B: 'come on man, no harm no foul'
Example B
Referee blows whistle for soft hands foul
Player: 'come on man, no harm no foul'
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.