schmerzelkender (pronounced shmer-zil-ken-dur) is a word commonly used in place of a profanity. Most common substitute is the 4 letter one starting 'sh', especially useful when you have dropped a wardrobe on your toe in front of your mother - see example 1.
Once proficient in the ways of schmerzelkender, it's most effective as a way of insulting people without them knowing - see example 2 (note - this will not work on someone who speaks German)
Example 1
Mother: "Careful up those stairs"
*thump*
You: "AAAAAAAAH, SHHHH...merzelkender"
Example 2
Idiot: "So when that drill bit doesn't fit in that lathe, do you know what that means?"
You: "Yup, schmerzelkender"
Idiot: "What?"
You: "It's the German word for exactly what you said"
Idiot: "Oh. OK..."
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.