A tuby is someone who blatantly fails at almost everything. Most of the time fat and if you were to compete with them at something they will be an easy adversary almost ensuring victory. (also a fat pink thing that dies very easily in the game defender for my htc inspire)
A tubby white cat with an extremely fucking short fuse, you pet him nicely and 5 seconds later your legs missing and while you scream in pain, he's shredding a hole in your back, this white little cock sucker is the first and last of his kind, he used to run and go brrrr, his face almost looks like a siamese cat, but he's not, he can barely open his fucking eyes cause Midder Cuddard has a second pair of eyelids that little som bitch!
A way of saying "Good thankyou" in code for no apparent reason and no one around you will know what it means because it has almost no likness to 'Hooks Tuby' (Clever eh?)
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.