I feel like this has somehow passed into the realm of urban legend as I've since heard a few similar stories repeated back to me but I used to work in phone support quite a ways back and we had a recorded call that we used to pass around to all new employees. It was a new computer user trying to figure out how to change the background of a document (I believe it was a web page he was trying to build in FrontPage but it could have been a PowerPoint).
The call went something like this:
[Call center introduction and customer response]
Employee: "So what seems to be the problem, sir?"
Customer: "I can't find where to change the background of my page. I've looked at all the buttons but I don't see a 'background' or 'color' button."
Employee: "I completely understand. Sometimes these types of things seem like they're hidden but it's pretty easy."
Customer: "It can't be that easy. I've been looking for over an hour."
Employee: "Well, it's in a context menu so they're kind of hidden. You can access those by going anywhere on an empty are of the screen with the cursor and then just right click on the mouse. It should pop up a little menu where the cursor is."
Customer: "Ok. Just give me one second. I want to make sure I do this right. I'm going to go get a pencil."
Employee: "Of course, sir. I'll repeat it again when we've done it once so you can make sure you write it down correctly."
Customer: "Thanks." [A few moments of silence] "Ok... so I move the cursor to a spot on the screen... [shoulder brushes receiver as he writes] ...C-L-I-C-K and then the computer will understand that as a command and give me a menu? Is that right?"
Employee: "That's correct. After you right click, you should see a little box pop up next to the cursor with a list of items. One of them will be 'Properties'."
Customer: "Do I have to wait? I did that and nothing has come up yet. How long do I need to wait for this menu to come up?"
Employee: "It should come up right away after you right click. Did you write click on the mouse already?"
Customer: "Yes, I did. I mean... my handwriting is not the greatest but hopefully the computer can still understand it."
The customer had used the pencil to literally write the word "CLICK" on the mouse. He didn't know that the left and right mouse buttons did something different. He thought they were for left-handed or right-handed use.