One of the biggest topics right now in high school parent newsletters everywhere is the Juul. It’s a popular e-cigarette system that looks a lot like a USB flash drive—you may have seen one in your teenager’s room, figuring it contains an essay on The Great Gatsby. Based on Twitter and Instagram posts with the hashtag #doit4juul, students are “juuling” wherever, whenever—in school bathrooms, in libraries and under their desks in class. They’re getting away with it because the device is discreet, the “cloud” can be hidden in a sleeve, and the vapor smells sweet and fruity, unlike cigarette smoke. Among teens, e-cigarettes are more popular than traditional cigarettes, and the Juul brand is currently king.