(n): excessive chatting between members of the opposite sex using a Facebook Wall.
In some egregious case, conversation may be that resembling an instant message conversation.
Usually indicative of a fore-coming hook up, relationship, or date.
Dan: "Look at this hot girl who keeps posting on my Wall"
Ray: "What, are you two having Wall Sex now?"
Dan: "At this point it's just foreplay"
When a guy pins a girl against a wall and fucks her. She is often wearing a skirt or dress. Great way to have quick public sex. Often anal. See also: skirt sex
Aly got pinned against a wall by Tim and experienced wall sex.
A series of wall postings on Facebook that has flooded your main page where there is obvious flirting or it is apparent that the two people are about to hook up. These postings are usually not wanted to be seen.
Related: Facebook Foreplay
"I was on Facebook and my main page was disgusting. I don't want to see Bob and Jill's Wall-To-Wall Sex!"