Any female who sleeps around. It is a widely known epidemic. Girls who are classified as Dirtybutts are also known to carry one or (usually) more STD's. They are known to fuck multiple guys in one night, and countless throughout the week. They will drive any distance at any time to get their fix.
Also known as "DB" for short.
That bitch is a dirtybutt forsure. She fucked both of my roommates and then tried to come onto me.
That bitch needs some TP for her DP... Actually, she needs straight diaper wipes.
Someone sporting a Venereal Disease. These are the ones that can often be found attempting to spread said Venereal Disease via the act sex while not informing potential sexual partners of their dickrot, or vagrot.
"Ol' dirtybutt scored him another one last night!"
"No, genital warts."