A tampon.
Ok admittedly, it was years ago and not the TSA, but a young male customs inspector. He pulled out a tampon from my suitcase, removed the paper wrapping and examined the entire mechanism of two cardboard tubes, a wad of cotton and a string. Then he looks at me and says, "What is this?"
I imagine he was subjected to some well-deserved taunting from his fellows in the aftermath.... Although, come to think of it, maybe not since there are apparently still some TSA members who don't know what a sanitary pad is.