A repetitive task usually involved in a Massively Multiplayer Online Role playing game (MMORPG) where a character's skill's are based entirely on killing monsters to gain strengths or levels. In most MMORPGs, there is no skill from the player involved, so anyone who plays 20 hours a day of grinding will be stronger than a player who does not. MMORPGs become a game genre filled with those who are too slow to play First-Person Shooters (FPS) or too dumb to play Real Time Strategy (RTS) but want to brag and be 1337 g4m3r so they play 20 hours a day and boast to "n00bs"
me_is_n00b: Johnny, what level are you?
Grinding_Johnny210: I'm level 250+
me_is_noob: wow you are so uber 1337! You must be so good at this!
Grinding_Johnny210: Yea, it's pure skill.
me_is_noob: I wish i could grind like you, unfortunately, I have a life, a job, a car, a girlfriend
Grinding_Johnny210: You suck n00b!