Really? I'm not so sure about that. If used informally couple means more than two.
http://www.dictionary.com/search?q=couple
Two items of the same kind; a pair.
Something that joins or connects two things together; a link.
(used with a sing. or pl. verb)
Two people united, as by betrothal or marriage.
Two people together.
Informal. A few; several: a couple of days.
Physics. A pair of forces of equal magnitude acting in parallel but opposite directions, capable of causing rotation but not translation.
And few is very vauge
http://www.dictionary.com/search?q=few
Amounting to or consisting of a small number: one of my few bad habits.
Being more than one but indefinitely small in number: bowled a few strings.
n. (used with a pl. verb)
An indefinitely small number of persons or things: A few of the books have torn jackets.
An exclusive or limited number: the discerning few; the fortunate few.