The slick and generally pulsating musclular appendages of hentai monsters, normally tentacular in nature.
"Hiroko watched, mortified, as hentacles blocked her means of escape and then methodically began wrapping her limbs in their slimytouch and forcing them apart..."
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.