We have a really unsafe behavior in the office where I work. Here's an example:
I just walked back from the bathroom and saw two of my coworkers eating delicious looking pieces of crumb cake. I made an immediate about face and marched into the kitchen like a zombie, cut a piece for myself, and took it back to my desk. I ate about half of it before I asked myself these questions, "Where did this come from?" and "Who brought this?"
A bad person could kill off most of the people in our office in about half an hour with a poison cake. We routinely eat anything on the break-room table without questioning the contents. Maybe next time, I'll find out who brought it before digging in.
If you want to see a reasonable facsimile of how quickly a piece of this crumb cake disappeared, watch this little video, but imagine it at twice the speed.