To describe something as very dry. A nasty is a Queensland term for vagina. The implication being that because of a nun's vows, her nasty will be dry.
Gee, we've had no rain for six months. This land is as dry as a nun's nasty.
by mt1 June 28, 2006
name given to the vagina of a catholic nun.
It's dam hot and i am as dry as a NUNS NASTY.
by MrMopar August 11, 2011