verb: On PLATO, a prank played on a derf. Sending out unpleasant or embarrassing messages under the handle (or "signon") of a person who'd forgotten to log out. Or ruining programs they've been working on.
verb: Hey Melvin, I just tried to run one of your programs and it looks like somebody got into it and put in a bunch of porn. Looks like you got derfed!
His dad caught him in the act and beat him to death.
I hate that DERF! He is so mean!
I hate that DERF! He is writing an incredibly rude and secretive novella about me.
I hate that DERF! Today, he was so annoying I had to pencil-slap him...like 25 times.
noun: the space underneath a man's scrotum before his anus; a normal person minus reason and accountability.
Dude, you only worked 3 hours today, don't pull a derf.