Crude way of saying "slut" in Japanese. Only used to describe
girls.
"yari" comes from the verb "yaru" when is used to mean "play" and "man" is
short for manko which is a derogatory way to say "pussy" in Japanese.
Basically it means a girl has or is a "playing around pussy"
There are not many BAD bad words in Japanese but this one will make even the most
liberal Japanese cringe.