1 of my favorite

"A customer called in with modem problems.
* Tech Support: "Ok, we're going to check your modem settings. First thing we need to do is make sure all programs are closed."
* Customer: "How do I know if everything is closed?"
* Me: "Make sure all windows are closed."
* Customer: "But...I'm in the basement. I don't have any windows here."
Lucky me, I made it to the the mute button in time!"
source:
http://www.rinkworks.com/stupid/cs_os.shtml
enjoy guys