It's basically a test a woman gives you to see where her boundaries are with you, especially early on. Some say it's also testing you for weakness.. challenging you to see if your actions are congruent with your words, if you are secure, or if you are an AFC in disguise. It's also a form of qualifying-and they want to see how you react.
What I have found interesting is, some things I have read said almost all woman do these sh1t tests in some form or another. I can't say every girl I have ever dated has given me one. What I have noticed, is that it's far more common among the better looking ones I've dated, where the tests are much more obvious, much more aggressive, and much *****ier.
The theory is kind of like this: An HB is constantly approached by guys, has been tricked in the past by guys who say things they are not, etc. So she has developed this as a method to weed out guys that are AFCs. If you fail the test as she has designed it, you don't necessarily lose the game. But she will make assumptions about you from this, and there will be more tests to come. Fail too many, and she will lose interest and move on.
It's very important to be able to recognize these tests when they come-that way you won't become too upset or reactive, because I won't lie-before I knew what these tests were, I wanted to smack the girl for being such a b1tch. Ironically, b1tch tests/sh1t tests are one of things that got my attention w/this PUA/DJ stuff. I had no idea I was being put through these tests, and when I read about it, and realized it was describing what I'd been through so many times before, I became more intrigued and wanted to know more.
Your reaction to such a test can vary quite a bit, and you'll still get a passing grade, as long as you keep a few basic principles in mind. The most important is probably don't try to win her approval. If she makes a comment about you that sounds like it's challenging you, don't offer explanations or excuses, like your trying to justify it to her. You don't have to get angry, but be firm in your response, and with vary degrees, probably the more aloof your responses are, the better. It's also important that you don't waffle or sound like your changing your position to be more palatable. In most cases-in the beginning anyway-even if she has a valid point in her comments or observations, if think it's a sh1t test, I am careful not to relent.
I've noticed these tests are more of a "mood" from a woman than a pre-planned scheme. Two, often easy ways to identify them. 1) They usually come out no where-everything seems fine, then out of the blue, she makes a comment that challenges or belittles you. It can be anything from something you routinely do that she fins annoying, to her saying something like "Please stop doing that." when you are rubbing her back like you always do (deciding she doesn't like something that she was previously ok with before). 2) Many times, because it's more of a mood, the tests will come in rapid fire succession, completely unrelated to each other. That's a tell tale sign that you won't ALWAYS see in a test, but if you DO see it, you're likely being tested.
Last thing to remember: In most cases, a girl giving you a test like this is a good thing in terms of her IL. Her qualifying you or testing you comes after she has some attraction for you or at least some interest in you-if she wasn't interested in who were as guy, you wouldn't be getting the test in the first place. So as annoying as it may seem (especially to AFCs that don't know whats going on), just remember that it's a good thing.