Easy solution. Just have your friend drive in front of you, then suddenly stop. You're behind them and gosh darn it, you had to slam on your brakes and skid to a stop too! If only that jerk in front of you hadn't stopped suddenly. Of course, if somehow the guy in front was asked about it, he thought someone was going to cross the street and hit the brakes just in case. False alarm, but it's a good thing that bloke behind him was paying attention and stopped too! Just practicing safe driving, nothing to see here.