Stack Overflow asks for your birthday in the format YYYY/MM/DD. Well that's kinda geeky! Only technologists format dates with the year first - I use it because it makes them sortable when in text.
But... what format is that? Why is it used?
If it were ISO 8601 format - it would be YYYYMMDD (no delimiters) or YYYY-MM-DD (hyphens as delimiters).