Argumentum ad cellarium
An argumentum ad cellarium is a logical fallacy and variety of ad hominem attack sometimes found in debates and comments on the internet. The argument is used to dismiss someone or their views by accusing them of lacking in the usual social and living skills that society expects, and thus being forced to resort to living in their parents' basement.
Although basement rooms are most commonly used for extra special derogatory factors, variants include demanding that someone get a girlfriend, or have sex - indicating, obviously, sexual inadequacy but also...
- (*knocking noise*)
...coming, mum! Sorry, have to log off, tea's ready. BRB!
- Martin's Law: "If during an online argument anyone accuses their interlocutor of living in their parents' basement, the argument is over and the accuser has lost."