Glob bowed to his sensei for the final time. Over the past few years, he had learned the art of unarmed combat from an esteemed master. Through grueling hours upon hours of training, he had focused his mind and altered his body. He entered the dojo a lost boy, unsure of his place in the world. He was now leaving a man, with a indomitable spirit and a body transformed into a weapon. As he left the hillside complex, he bid farewell to his fellow students, slung his pack over his shoulder and set out into the world.
Eventually Glob would join up with an adventuring group, eager to prove his worth and destroy the terrible stereotypes of his people. You see, Glob was a goblin. A goblin trained in the deadly martial arts, but a goblin nevertheless. Townsfolk viewed him with suspicion, and even his own companions openly speculated on his ability to hold his own in a fight.
Still, Glob trudged on, determined to see through his dream. The first encounter the group had was a rough one, with a trio of bugbears proving to be too tall a task for the diminutive dynamo. Glob was roughed up pretty good, but his confidence was undeterred. He just needed some more experience.
As the weeks went by, Glob continued to be pummeled on a regular basis. Kobolds, skeletons, pirates, and even some fellow goblins had their way with the green skinned gladiator. His team began to laugh each time he was kicked, punched, or clubbed into unconsciousness. By divine providence, Glob managed to stay alive, but his value to the group went from productive and respected fighter to comic relief.
Finally, having been nearly eaten by a cave spider, Glob decided he had enough.
"This sucks, I want to make a new character", Glob shouted, throwing a crumpled up piece of paper at the dungeon master.
After months and months of trying to convince his DM that a goblin martial artist was a good idea, the head of the gaming group had finally relented and allowed the unusual class/race combination into the game. While at first the novelty was fun, over time the fun wore off and the character became increasingly useless until finally the last vestige of fun was gone and the player running Glob(that would be me) openly pined for his death, so that a new character could join the group.
The dungeon master had warned me about the stupidity of playing such a character, but I had insisted.
"It will be fun!", I told everyone.
In the end, it was not fun, for me, while everyone else seemed to thoroughly enjoy it, even the DM. So as long as the character is not overpowered, be a good sport and say yes to your players. Even if one of them insists on something as utterly dumb as a goblin martial artist.