Tätiä itsekin ihmetelleenä...
Tällaisen löysin googlaamalla:
Aunt Flo was Sharon's aunt, who would come to visit the Marsh residence once a month, and stay for nearly a week at a time. This would turn Sharon into a bitch. In the episode Spookyfish, Aunt Flo gave her great-nephew, Stan, a goldfish for Halloween, but it was evil, and killed many people, including Aunt Flo. This upset Sharon, because Aunt Flo would not come and visit her anymore.
Aunt Flo is an obvious reference to the menstrual cycle, and her death parodies the menopause.
Tää Aunt Flo on siis South Parkin hahmo, ks.
http://southpark.wikia.com/wiki/Sharon_Marsh#Aunt_Flo