Head over to one of the bus dealerships, select a bus from the terminal, and get in it. Drive it around to the back of the shop, and you'll find some cones laid out in a slalom; complete that course without hitting a cone, and the achievement will pop.
It should go without saying, but it's easier to do this in a smaller bus, I like the Citaro K for it. If you do hit a cone just do a loop around the building and when you get back to the beginning of the course the cones will have reset and you can try again.