Why do girls talk about each other?

So, today was the first day of gym, and I put on a regular pair of spandex, biker shorts. These 3 girls where saying 'Oh hey let's were our spandex!' and then laughing about it, and saying 'Oh, she's got spandex shorts on!' And they arnt bad, they are regular work out shorts, and other girls where wearing shorts shorter than mine. I'm scare to confront them, and Im scared they are going to start rumors about me. HELP.