Pretty much sexual intercourse with clothes on. Occurs a lot in small public gatherings where two people show interest but are disinclined to actually take it further. So to make up for it they cuddle closely, even straddling each other slightly, thus the "fucking" part of the word.
Wow, those two are definitely cuddlefucking in that seat
Bob and Steph are cuddlefucking on that seat, you might not want to sit close to them.
When the leader of the evening in your posse deems it time to leave the Club. They then proceed to gather the group but not head towards the door. Thus causing a jam up in traffic that forces you to stand uncomfortably close to your guy friends.
Josh - Yo lets get out of here
10 Minutes Later
Mike - Come on.. enough of the Cuddle Fucking lets move! Adam is running up the back of my legs and I Brent looks like he can't breathe!
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.