how your average person expects the software to work
I once had the privilege of working with a fellow who had a talent for doing "the unusual". Got used to running new code past him, and trying to stifle my urge to ask "Why did you do _that_?", because if one person felt a particular action "made sense", then there may be more, and maybe I should consider not "What I expect them to do", but "What they might do"