A student at East Stroudsburg University in Pennsylvania has been charged with using the SnapChat online app to sell drugs out of his dorm room. University police began investigating because of increased marijuana use on campus this year before arresting 18-year-old Jahmir Mapp on Wednesday. Authorities say Mapp sold marijuana to about a dozen students daily using SnapChat. The mobile messaging app lets people send pictures and short video messages that disappear shortly after they’re viewed. Authorities say Mapp’s SnapChat activity shows he also sold cocaine and the anti-anxiety drug Xanax. Police say they found a small amount of marijuana in Mapp’s room, wrapped in clothes dryer fabric softener sheets to mask the scent. Online court records say Mapp applied for a public defender, but that office said Thursday it doesn’t represent him yet.