DYFN
IM chat acronym for "Dude, you're fucking nuts!"

Developed by 0gre and Methangel whilst pondering how to pwn teh intarwebs...

DYFN is used to describe that the actions of one are remarkable, even retarded.
Methangel: I decided to buy a Mac today.
0gre: Umm...
Methangel: It has really cool graphics, I really the the gui too.
0gre: DYFN!