Rule for software developers. Never stand over the shoulder of a beta tester. Once, I was watching Jane test the latest version of our software. When a message appeared on the screen, "Press any key to continue", Jane pressed the letter 'j'. I thought I was going to have heart failure. "JANE!" I screamed, "Why did you press J?!!?" "It said any key." "Yeah, but....when programmers say any key, they mean the space bar!" At which point my fellow programmer looked at me and said, "We do? I thought we meant enter."
(From the "Rest" of RHF)