By definition Analinguis is performing oral sex but instead of sucking the genitalia of someone, it's the ass that is being sucked.
Basically, it's sucking ass... literally
That girl performed an Analinguis on me, she sucked all my butthole while having oral sex with me!
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.