Just because it looks innocent, do not assume it is.  A guard at the federal building in Detroit found a bag left outside the doors and thought that someone had forgotten it.  As a favor, he took it into the building and placed it under the guard desk just in case the person who lost it came back.  He was trying to be nice.

The bag sat for two weeks under the desk until two other guards became suspicious and had a federal inspector look at it.  It was an improvised explosive device.