I was working in the corporate headquarters for a large agriculture/construction equipment company. The year was 1994, and many users were moving from the green-screen RS-6000 terminals to Windows for Workgroups with TCPIP (yeah.).  I was asked to install a new PC for the guy under the CIO, replacing his terminal.
I dropped the desktop to his office, then showed him how to log on, etc.
Me:Â “Ok, move your mouse to the terminal emulation software and double-click.”
User picks up the mouse and holds it on top of the terminal icon and double-clicks the icon. Against the monitor.
Me: “Umm…ok, the mouse works on the mouse pad…and I’m going to leave this icon here for you to practice with the mouse, it’s called ‘Meet the Mouse’.”
Exit, stage right.