It means being very aggressive by doing nothing. You know, just like a woman.

Passive agressive is a psychological term to describe particular patterms of behaviour. A passive agressive behaviour is exhibited when a person does not openly react to other people's behaviour that upsets them. Instead they withdraw, becoming resentful, sullen and unco-operative. Whereas open anger is obviosuly agressive, this kind of masked anger, where the person doesn't do or say anything about the problems, is termed passive agressive, because it is a form of agression that is expressed through passivity either doing nothing at all, or doing things badly, or with the least possible amount of energy.