mom's basement
Stereotypical home for the geek, nerd, fatbeard, loser, etc. The term implies that the individual still lives with one or both of his parents despite being a grown man. Reasons for still living at home may include a lack of drive and ambition, being unable to afford a place of his own due to spending all of his money on his hobbies (i.e. Star Trek figurines, comic books, and online role-playing games), or just plain being a mama's boy.
"Jeff is such a loser. He really needs to move out of his mom's basement and work on getting laid rather than spending every free minute playing World of Warcraft."
mom's basement
the place I live in
I live in my mom's basement
CSI: Mom's Basement
CSI: Mom's Basement is the term given to social media warriors who, (from the safety of mom's basement or some other hermetically sealed room), convict a public figure or high profile suspect based on fringe blogs, poorly sourced media, or personal biases.
So, you're just going to decide she's guilty based on a couple tweets and your own prejudices...what're you, CSI: Mom's Basement?
Living in his mom basement
Worthless losers that live with their mother despite already growing up.
He should stop living in his mom basement while watching hardcore porn and smoking drugs while fapping all day.