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1.
fex
Turd. Fex (or faex) is the singular of the Latin word feces (or faeces). Although feces has entered English as a mass noun, fex retains the original meaning of a single, discrete piece of shit.
John said his girlfriend Sarah was a fox, but when I pointed out her lumpy shape, terrible odor, and weight of only 18 ounces, he admitted that she was, in fact, a fex. He cried and cried after we flushed her, and claims to this day that she was the only woman who ever truly understood him.
by Zachariah Zuckerman September 24, 2008
 
2.
Fex
To trick a virgin (mostly females) into having sex with you. In order to have true fex, the said virgin must believe that they have kept their virginity after penetration.
Dude, did Harry have sex with his girlfriend yet? No better, he had fex with her. Wow, what an ass.
by Harridee February 19, 2010
 
3.
Fex
Fucking Excellent.
Dude, that party was fex.
by spleen2 July 25, 2009
 
4.
fex
When two obese (fat) people engage in sexual activity.
Hey, my huge ass step-mother, just banged the fat ass neighbor.

Wow man, that is genuine fex.

Damn, with you're badoingy ass; lets have some fex.
by Hen-Pen Beard Man June 23, 2007
 
5.
Fex
When a guy and a girl are having sex, and the guy likes to look at her pictures online, to keep him "in the mood" and remind him that she's WAY hotter online than in real life.
So how was Laura Diggelhoop last night?
Dude, I had to have fex with her!
by peachykeane December 07, 2009
 
6.
Fex
To have Facebook sex; i.e. engaging in and having conversations with an attractive male or female over Facebook. Also, any flirtatious interactions between two members of the opposite or the same sex via said social networking site.
"Dude that chick's profile pic is so hot. We're totally going to fex tonight."

"I just fexed with Johnny! Maybe he'll ask me to Prom now."

"He's a fexer; we fexed over Facebook Chat earlier today."
by ReginaAlice December 01, 2009
 
7.
FEX
acronym: Future EX (boyfriend/girlfriend)
OMG that guy is SOOO guna be my new FEX
by bunbuzz October 22, 2009