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!
Jeremy and I were totally going at it when I mentioned something I had no idea would start a fex; I didn't realize how mad he was until he lost his boner.
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."