Yeah -- I like that. :-)

if it's extensible, then it's custom(izable) anyway. so how about...

"eXtensible Fast Computing Environment" ?

this is not too bad IMHO. it also gives a clue that XFCE is modular.
(i avoided "extendable" or "expandable" because it sounds much like "expendable".)

X - Xcellent
X - Xtreme or Xtremely
X - Xistential (OK, that's a stretch)
X - Xisting (that one stinks)

You can probably come up with some others. 

X - X11
F - Fast / Free / Flexible / Functional
C - Custom / Computer / Computing
E - Environment

how about these ?
my personal preferrence is "X11 Fast Custom Environment".

X11 Free Comon Environment
Xtreme feature-rich Common Environment
X11 Functional Common Environment
Xorg Free Community Environment
X11 Fruit of Community Envirnment
X11 Fork from Common Environments
X11 Free Centric Environment

all this for now
But if Xfce/XFce/XFCE/xfce is the same why no simply use XFCE And Xfce for convenience making both officials??

^ thanks, but i've read that before.

however, there is still a discrepancy between this description and the logo.
and on the bottom line, XFCE/Xfce is no longer an acronym anyway.
given all this, isn't it about time for some new name ?

I guess that's for the developers to decide! I know some people get confused between Xfce and LXDE. You could propose a naming competition here on the forum, jens.

however, there is still a discrepancy between this description and the logo.
and on the bottom line, XFCE/Xfce is no longer an acronym anyway.
given all this, isn't it about time for some new name ?

From the wiki:

"The name Xfce originally stood for XForms Common Environment, but since then, Xfce was rewritten twice and doesn't use XForms toolkit anymore. The name survived, but the F is nolonger capitalized (not “XFce”, but “Xfce”). Currently the acronym doesn't stand for anything (suggestion: X Freakin' Cool Environment)."