Ferment

[Sarah]

1. the art of 'mellowing' or cooling down when one has previously been in a bit of a furor,

2. to receed from a heated discussion or outburst.

[Ernesto]

(of a substance) undergo fermentation.

[Michiko]

The act of staying in your room for days at a time, not showering, and avoiding social interaction to the point of becoming a greasy, unhealthy slob. Usually accompanied by heavy use of the internet and/or video games. A fermenters natural habitat is typically found in the dark corners of sites like 4chan, reddit, and twitch.
Once you start to ferment, it can be hard to get out, usually requiring some sort of [wake-up] call from the [outside world]. Some fermenters never get this wake-up call or ignore it, resulting in a lifetime spent mostly in their rooms.
[Fermentation] can lead to later complications such as depression, anxiety, anti-sociality, obesity, diabetes, and more.