Don't start feeling guilty just yet because chances are that her nagging has very little to do with you. But in all fairness, if she "asked" you to take out the garbage ten times and then "tells" you to do it before she empties it on your convertible, then you could be part of the problem. Nevertheless, she is overreacting a bit.
Here's why she keeps on keeping on...
Most women nag because it is in their nature to do so. They grew up watching most of the women around them doing it and were taught that it was the best way to handle men and their occasional inability to function on a normal human level. This applies even more so to the women who are just coming of age, as they were brainwashed even more by television shows like Roseanne , in which the entire emphasis was on pointing out men's many failings.
The big picture
Sometimes women nag over some seemingly insignificant thing in order to work their way onto larger issues. She knows that it is going to get you peeved and plans on using that anger later to bring up whatever it is that is really bothering her.
She's a little loopy
Have you ever thought that perhaps she's just plain crazy? I know that it's hard to accept, but when it comes down to it most women are at least mildly psychotic, if not full-blown lunatics. So remember, if she is indeed a wacko, when the nagging starts, don't push her to the point of dismembering your favorite member.