Kirstin comes from Tennessee, and she speaks with an accent that is sort of a combination of the hippie California thing and an Appalachian drawal. It makes everything she says much more quotable, especially given the fact that she's usually pretty worked-up about anything she says. Among her famous quotes are:
"It's not gross, it's just dog sex!
She's gotten to the point where she uses such lines for rhetorical effect.
I won't go too far into discussing Kirstin's love life, but let's just say there was a time when she appeared to be doing stuff with Monster Boy, and more recently there was a thing with Johnny Two Boom, who more or less jerked her around in a manner that was at times painful to watch.