In Tokyo, white button-down shirts are about as ubiquitous as the poorly concealed nipples underneath, and, according to a 2013 survey, most folks do not welcome the sight. One might suggest simply looking away, but, let’s face it, avoiding eye contact with purple nurples is like ignoring glowing eyes in a dark forest: not possible.
In Japan they go as far as to create a t-shirt that is designed specifically to be worn with button-downs.