Originally Posted by mitchc
Now serious answer, the only way to stop them is to slow down (gently off the throttle) and they'll soon get bored and find another victim.
Just slow down and enjoy the scenery until the louts clear off.
Ive never had any hassle in this respect though i have witnessed it in the US.
I would think that Mitchcs solution would be the best solution.
Right away you've given them no wake to ride along with a clear message that you don't want to play. All without winding anyone up or causing friction.