This term describes the nightly experience of those unfortunate schmucks who just absolutely cannot fucking fall asleep, no matter how much thrashing around in bed they do or how much ruminating over past mistakes they indulge in. Instead of falling asleep, an insomniac is simply failing asleep.

To sleep during an online conversation. This can be due to the conversation taking place late at night, being really boring, and/or the person in question being tired or (more commonly) drunk.

The term can also be used when someone is being slow at responding, should you suspect that they have fallen asleep.

a term used mainly on 4chan to tell other anons that the mods are not watching, mostly used to get a link to an illegal dropbox

Neglectful of an important task or responsibility

used as an excuse to make up for trying to not be wrong or lying.

In a state of unconsciousness similar too or identical to that of heavy alcoholic inebriation or getting knocked out by a heavy weight boxer

The act of falling asleep at an unreasonably early hour while in the presence of guests.
Usually this will also consist of passing out on the largest piece of furniture; depriving someone of a place to sit.