Keyshawn Johnson chased down Justin Bieber and confronted him on Bieber's front lawn
He (and someone else) called the police, but then Johnson went a step further, according to reports, and hopped in his Prius and chased down Bieber's Ferrari.
He apparently made it all the way to Bieber's house, where he tried to confront Bieber, who ran inside and wouldn't come out of the house.
Bieber also declined to speak to police about the situation.
He might want to slow down in the future. Even though Mike Tyson is Bieber's boxing coach, I'm pretty sure Keyshawn could probably take him, if it came down to it.