It's funny how the mind works.

Once I was teaching computer basics (use a mouse, parts of a computer, use Windows, etc..), and I told the students to move their mouse up and to watch the pointer move. I heard someone say "It's not moving!" When I looked over, she had the mouse in the air, lifting it. I held back a giggle, then said, "No, forward." She leaned forward in her chair, mouse still in the air.

Funny thing is, that's happened a few times over the years.