April Fool failure

The Joke:
put a USB thumb drive in the back of the computer that boots dos & has a virus like message in the autoexec.bat we used "All your base are belong to us"
then send the eicar virus test string
http://www.eicar.org/anti_virus_test_file.htm
to the hard drive via \\computername\c$
the AV will catch it and display a message
then call the user on the phone and ask if they received any suspicious email because the Corp AV server is reporting a virus on their computer.
they will associate with the eicar virus warning
tell them to reboot their computer to be safe
when the computer reboots it won't enter windows it will only boot to the dos prompt with the virus like message
Wait for the help desk call and say that everyone in the IS department is busy fighting a virus outbreak.

Result:
we got caught when the USB drive was inserted and autoplay was enabled. Make sure your victim is out of their office and their boot sequence includes USB