A teenage girl usually (14-18) who continually does things that are bad for her in order to find love and affection from a man. However, this young woman rarely finds what shes looking for. -Comes from the way the main character pronounces name of the promiscuous-hippie character "Jenny" in Forrest Gump.
Dude, that Alex girl is such a Jenn-ay. I swear she never finds what shes looking for.