TFAS
The term TFAS was coined around 2007 by the member Merchelo(gg etc), and has since gained popularity among the regulars.
A TFAS is usually declared in #lobby or other SRS BSNS channels when a user expresses their need and intention to excrete human faeces.
TFAS, in it's original form, stands for:
Time For A Shit.
Other Variants
TFAP: Time For A Piss: Fairly easy to understand, a user expresses his/her intention to urinate, and goes and does so.
TFAF: Watch out for this one. It stands for Time for a FAP. (FAP FAP FAP FAP etc.)
TFAS Etiquette
It is generally accepted that when members return from a TFAS, that the TFAS is measured on the http://en.wikipedia.org/wiki/Bristol_Stool_Scale.