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9.
a sexual function
The man performed a fucktion he learned from his ex involving rolling and lube.
by tvaiello December 14, 2010
 
1.
When you are doing Calculus function problems and obviously there's something else on the
mind.
Rick: "What the heck would f(x) equal? I hate fucktions!"
Esteban: "Hahahahaha... nice"
Ms. Rod: "What kind of problems are you guys doing?"
Evan: "That, my friends, is called a Freudian slip... haha."
by A Breed of Sushi January 25, 2009
 
2.
Similar to fiction; Tale of sex that never actually happened.
Ummm...Remember when I said I fucked Becky and her mom simultaneously? That was actually fucktion.
by goatsearse May 11, 2009
 
3.
the heat generated by having sex
Gosh, it was cold in here a few minutes ago, but it's warm now--must be the fucktion
by Mike Reilly October 17, 2003
 
4.
Erotica, erotic fiction.

Related to fanfucktion.
They're claiming that her new book goes under the Romance genre, but it's really just plain, simple Fucktion. There's no emotional connection between the protagonist and her partner.
by Gale Gynoid April 27, 2010
 
5.
A function that's totally fucking your maths.
(In reference to a page of mathematical derivations)
This is impossible! This fucktion is ruining my shit!
by PhysicsProcrastibator October 25, 2010
 
6.
The suction created in the vaginal or anal region during intercourse. This physical phenomenon will not occur with small cocks. It, in fact, takes a considerably large one (typically) to accomplish this feat. Other items can be used to accomplish this doe.
Jenny-"So, how was Paul last night?"
Laney-"He was fine."
Jenny-"Was he big enough for any fucktion?"

Laney-"Please, he wasn't nearly big enough... fortunately he has other ASSets that compensate for his small ass dick."

Jenny-"Damn, it's hard to find someone big enough for that doe"
by dav-o March 17, 2014
 
7.
To have a mind full of fuck.
mish: you're brain can't even fucktion right now
by Kinnipop January 22, 2011