How to do such a mistake?
Should the private part be exposed, you will look, by reflex
action. That is not a mistake.
If you lift up the skirt, pull down the panties, that cannot be a
mistake, as your lawyer would try to tell the judge.
Unless,
You are very myopic, and not wearing your glasses. You saw your
wife in the kitchen, grabbed her and carried her to the bedroom and
pulled down her panties and saw the fuzz.
Put on your glasses and saw that its your maid wearing your wife
dress. 
Mistake.
