Once I worked in a blood bank and we were getting crank bomb scares (it was the 80's).
We would call the police and close up shop.
On the weekends, the switchboard was closed and all calls went through the Lab. I overheard a lab employee say that they got another bomb scare call, but since all the others were phoney, they laughed it off.
Once I heard, I told the charge nurse that I wasn't planning on my family having to find my body in the rubble the one time there was really a bomb!
We closed up shop and put a note on the door saying, "Closed due to bomb scare."
The donors who came in asked if they still get their T-shirt even though they couldn't give blood!