Paris, Friday evening, 9:30 pm. Hundreds of skaters are hanging out at the bottom of the Montparnasse tower, waiting for the start of the Friday Roller Tour. A few minutes later, they will be up to 20,000 at the starting point. Together, for about three hours and over about thirty kilometres, they will glide up and down the streets of Paris on roller skates. Due to the crowd and to the participants' mobility, finding a friend is challenging. The main problem for friends participating in the tour is to find each other during the pauses, if they were separated after the start. Currently, in order to locate a friend, a participant should: (1) call his friend, using a cellphone, (2) describe the environment (street name and number, shops name, monuments, etc), and (3) according to the environment description, try to discover if the friend is forward or behind. In order to make it easier to find a friend, we propose a Bluetooth application to be embedded in cellphones. This application's ultimate goal is to provide users the ability to discover, not only their relative position in the tour, but also the positions of their participating friends. The application acts in two steps. First, it calculates the current relative position of the user (positioning), and then, through a communication protocol, sends this position to a user's friends (locating). In this demonstration, we do not consider the communication between skaters, but focus only on positioning.