When a guy and girl are sexually intimate, the practice of the guy to alternate between bottom and top holes (anus and vagina). No particular pattern of action is required, and the switch-off can be completely random (ie: top, top, bottom, top, bottom, top, bottom, bottom, bottom, top, fist).

Create special patterns to signify festive or celebratory events and occassions; re-live these occassions through fantastic, nostalgic sexual practices!
Donnie: Tim was derfing Julie and covered her vagina with shit.
Darcy: Goddam! O_O
by Pwnforce United December 23, 2005
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A bipolar vampire that is AWESOME!!!!!
1. I am not DERF.
2. You are such a DERF.
3. DERFs are so annoying but awesome at the same time.
by Zachary Max Zimmerman January 17, 2009
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Amazing, Happy, awesome.

If you spell it backwards it spells Fred.

A charecter on fred the movie.

The number between 5 and 6!
I feel derf today.

Dude: Hey fred!

Other dude: Yo it's Derf.

Freds twin in the movie Derf.

Kid: 5, derf, 6, 7.....
by scenequeen11 December 30, 2011
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verb: to do something stupid, immature. to lack rational judgment.

noun: the space underneath a man's scrotum before his anus; a normal person minus reason and accountability.
I can't believe I stapled my scrotum to my chair again. I really pulled a derf.

Dude, you only worked 3 hours today, don't pull a derf.
by Derfilicious December 16, 2007
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"Oh my God, You derf! What the hell did you just do? You Fucked everything up!"
by Emily May 06, 2003
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"Derf" is a term that refers to the hair that grows on the perineum (aka "chode" or "taint")
Make sure you shave your derf before asking a lover for a rim job.
by blanatan July 16, 2006
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More fondly refered to as "derf" or "derf-derf" he is the most idiotic and worthless kid in my psych class. He laughs at everything you say to him which more often than not is an insult, usually referring to his step-mom who has fake titays.
hey derf, you ever see your moms fake boobs? cause you are worthless like that
by Jeff January 31, 2005
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