Disturbing new footage shows young users of 'zombie' vapes convulsing in the street - as evidence grows that the drug -laced pens are already being sold on the black market in Britain. In one new clip from mainland China , a teenage girl is seen lying down in front of a corner shop with her two male friends as she appears to shake uncontrollably. A startled shop worker looks on as her two friends, apparently undisturbed by the incident, sit idly by. Later, a voice is heard calling for someone