Word commonly used to respond to a request or statement when the user does not understand any of the words spoken. Word can also be used to describe a situation where the user is perplexed of an outcome ie unexpected death on a computer program where there is no answer to the reason why.
Word can also be used when joining a conversation mid way allowing the others to know they would like to be informed of the latest progress or better understanding of a person or object in question.
Female to female "... And you know mikes girlfriend is going to be eating a lot now because of you know what."
Mike turns round "Whojawatnow?"
Male "......500/120 res with 32bit prosser and 3gb of ram, it runs all programs of that spec"
Male "Whojawatnow? I asked you if you wanted a pizza."
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.