I got our agency good this April Fool's.  We work in a historic warehouse in Minneapolis. Beautiful space... hand painted tin ceilings, VIP red carpet ramp, garage doors on the coference room among other things.  The office is very open which allows for needed collaboration and offices are all glass so natural light comes in. 

I took advantage of the fact that everyone loves that and had the CEO send out an email saying we were moving to an office park in a suburb of Minneapolis for a number of reasons re: issues with building management, issues we've been having with our HVAC - so it was very believable.  I researched the building, made sure if any one googled it they could see the location, square footage available, etc. 

Shortly after I had our office manager send out a follow up email which detailed the move to take place in one month and how everyone needed to help with this move to make it go smooth.  Along with the email I had him send the attached floorplan.  Clearly opposite of our current collaborative layout.  Many more offices, cubicles, etc.

It was interesting to read the responses. Some people were very upset by the news, others commented on how it would be cool b/c it was closer to their homes, and there were a few who are relocated to our NYC office who thought they did their move out there in just the nick of time.

A few souls figured out the prank and helped play along for the others who were trying to find out if it was real. 

Needless to say, we got the angency rolling pretty good.