1. To get a stamp on your completed homework.
2. To act crazy and/or insane while teaching or just talking in general.
3. To yell at one's smart board.
4. To flick off one's class.

5. To stand on a desk to feel if the air is working.
6. To teach "shit"
7. To throw markers at ghetto kids.
Person A: "Yes I derfed my homework!"
Person B: "Ugh, lucky, I skipped one problem."

Teacher: "You guys forgot your calculators?!!!!" "YOU'RE ALL LOSERS!!!!!!"

Teacher: (to smart board) "WHY ISN'T THIS THING WORKING?!"

Students: (to teacher): "Happy Birthday!"
Teacher: *flicks off class and walks out*
by calculusstudent November 23, 2012
A person of extremely high and incomprehensible intelligence. A genius of monumental and baffling proportions.
I wish I was just a derf. Then I would know the answers to all the questions in life.
by binchaser September 01, 2008
a # between 5 & 6 sometimes used as something you say when you are mad
oh derf! or one,two,three,four,derf,five
by mabgywugewinuygcyugbayhgrvn8sb February 07, 2010
A person of unusual agility and skill.
I don't really want to play her. I hear she is a derf.
by 2forme November 12, 2007
A derf is another word for the unwanted. the person no one wants/need. the loner. the suspected pshyco killer. it can also be another word for tool, widely known as somebody no one needs (annoying). an extremely BIG insult.
Can you believe that effing Derf? what a tool!
by CoUnTrYwOrLd July 06, 2011
A word used as a censor for the word "Fuck". Can be used in any tense that "Fuck" can.
What the derf is that?
May I please derf that bitch?
You are derfing insane, homie.
by Money Blimp January 25, 2010
another way to say the word "duh" almost like obviously
Person 1: Wait why are we going to the mall?
Person 2: To go shopping, derf!!!
by yeah3xyeah3xyeah3x March 11, 2011
Synonymous with a skilled ninja. Often used to describe a quick and fierce enemy who is extremely agile and deadly.
Person #1: There's that girl Sarah, lets go beat er' up.
Person #2: Fuck that! She's a derf! Im leaving her alone.
by Slimescree December 17, 2007
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