First find a cop car, this is the only vehicle i found that could do this, next find a building that has flat walls, sounds easy but most buildings have like a block trim around the top or middle, anyway what you want to do is get the police car vertical on the building to do this keep accelerating and reversing scraping against the bottom of the building you will also need to turn into the building while accelerating and turn away while reversing....actually just mess around wid the turning its pretty simple. eventually you should go vertical on the building then you u can drive up and down the building and get off at the top of the building if u want. (ive only tried this on offline play)