Is a mix of two words, mig (that comes from catalan languagge and it means half) and the english word brain.
So, it's an adjective and describe somebody that is stupid
A mentality of excessive concern or delight in the enforcement of obscure rules or minor offenses by a moderator or officer, often in opposition to the stated purpose of said rules.
1. A mod deleted my post because it was too short by 5 characters; this subreddit is overrun with modbrain.
2. A study from Pepperdine found neckbeards are 78% more likely to develop modbrain than the general population.
3. My keys were in the car door when a modbrain meter-maid gave me a ticket.