In the movie Superbad, Seth (Jonah Hill) dances with a girl at a party. He's pleased with this achievement — until she leaves, and Seth discovers a small period blood stain on his jeans. He's disgusted. This was a big moment in Superbad, so much so that my friend Nick recounted it for me at lunch after the movie came out. In laughing at the joke, we sympathize with Seth, who's grossed out. We should really be empathizing with the girl, though. After all, the joke is at the expense of her exploring her newfound sexuality at a party when her period ruins the whole encounter. It hinges on shame.