What's sex got to do with...Graffiti?

I don't know if it's just me, but I've noticed only a few bathrooms on campus that have graffiti in the stalls, and the only place I've noticed that has extensive graffiti is Lind hall, home to both the English department, including their TA offices and student groups, and the College of Science and Engineering, including their advising and student groups. Interesting mix, no? The result is some interesting graffiti with great literary quotes, math jokes, feminist declarations, and a few initial-filled hearts too. But the other day, I noticed an interesting group of scribbling that I thought particularly applied to the class and decided to document it for the blog.

There's a lot going on in this chart. Of those responding, 60% are decidedly virgins, 40% non-virgins (did you notice that there is no word for some one who isn't a virgin?) and 8% wish to say "Hell no" to virginity. The statistics seem to say the reverse of what pop culture would say about college students; apparently, the majority of those frequenting this bathroom are not actively engaging in sex. Furthermore, those that most certainly are active have been labeled "sluts" and "hoe(s)."
Why do you think someone decided to start this chart? Why are we curious about each other's virginity? What do these numbers tell you? What role are fellow women playing in the sex/gender/desire matrix when they call each other sluts?