They're doing construction in my building, so he didn't hear me walking behind him. I was looking down and flipping through e-mails on my black cell phone, when he must have felt my presence. He glanced behind at me, and instantly stumbled forward while reaching for his belt.
Then he quickly composed himself and said, "Good morning." I replied with the same and didn't realize what had happened until a few seconds later.
He thought I was holding a gun.
Now, let's run this out to its inevitable conclusion. Because these policemen rightfully have their eyes out for suspicious things (someone carrying a gun). Yet, if you look around the college campus I work at, 99% of students are walking around, heading to class, head down, eyes on their phone. If this policeman got confused, somebody, somewhere, is going to try banning black cell phones for national security reasons.
As far as scaring a police officer, yeah, it felt pretty good.