When someone goes flying by me I follow along about a half mile behind and let them probe for cops.

Had a friend in school once tell a story about speeding with another driver ahead of him and all of a sudden there's a cop on his ass, lights on. Buddy pulls over to the next lane and the cop points at him and continues to go after the other guy.

When he told the tale, he said he got lucky and the cop pointed at him to warn him before going after the other guy.

I later realized that he probably got lucky that he failed to understand the cop was trying to pull them both over, but nothing came of it (that I heard of anyways).

It is called a fuzz sweeper, follow a raging asshole that is speeding.