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6.
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
15 8
 
36.
a retartedly, annoying white girl; usually very ugly
that stalker gurl is a mad derf
by Anonymous March 08, 2003
9 132