A shit test is when a woman gives a guy a hard time, usually for the purpose of seeing how he will react. Because women (especially attractive women) are hit on all the time, they have developed behaviors that quickly disqualify potential suitors that are not of a high enough value for her. The shit test is one way to do this. Shit tests can be challenges, IODs or reframes.
Saw this exchange between one of our students and a girl recently. He was playing cheesy pickup line anti-game game. The way it was handled was not only excellent, but spiked her attraction enough for them to be making out an hour later.
Him: "If I told you you had a nice body, would you hold it against me?"
Her: "I have a Taser in my purse. I can hold that against you."
Him: (bare ghost of a smirk. Laserbeam eye contact) "I sensing some electricity between us."
Her: "Really? I'm sensing resistance."
Him: "We're past that. Now there's definately a spark."
You'll notice that she was shit testing him for intelligence. Most of the time shit tests fall in the realm of social intuition and self confidence. When you are picking up top tier girls, remember that a good number of them are not only beautiful, but extremely intelligent and educated. Bring your "A" game.