The Hospital Gown

A johnny, also called a "johnny coat," "johnny-shirt," "johnny gown" or "hospital johnny," has been called "the great equalizer" because it puts all hospital patients on an equal footing with the staff.

Obviously, the gown was originally designed to maximize access to the patient's body by medical staff.  According to several nurses, they say it got the name johnny because going to the "john" is a lot easier in one of these gowns.

That makes as much sense as any other explanation.

Now...check out these designer johnnies! Designer Johnnies