Basement Monster 

Someone who never leaves their own home, specifically their room.

Have you seen Derek lately?

No, he's a basement monster man. I don't even think he showers.

Basement Monster by SJeffries April 8, 2009

basement monster 

The basment of one of your friend's that has a monster living in it. This monster never actually is seen but its presence can be noted when large amounts of weed magically disappears in the basement. It is also known to take lighters, controllers, and any other item that would be useful at that time.

Person 1: Dude, we just lost 5 ounces of purple haze at Jeff's basement!!

Person 2: The basement monster attacks again

basement monster by basementmonstervictim September 13, 2010