A phrase borrowed from Pop Art. 
After sticking rigidly to blue, white and varieties of stripe for a number of years (about a dozen or more) I've begun experimenting with colour once more as regards button-downs and, to a lesser degree, polo shirts.  The first acquisition, around last October, was an interesting Ralph Lauren (thick cotton, with rather too pronounced a placket) in yellow.  I'm not sure it'll work.  But a more recent buy, an old Brooks, does: a softer, more buttery yellow.  Looks good worn with a navy cashmere v-neck - and might look even better under a navy crew-neck (again, I think, cashmere would be preferable; perhaps merino).  Green I'm ruling out unless it comes on one of those rare Brooks items: apple and ecru almost?  But pink - if very soft - I'm once again thinking about.  It's the 'glare' that should be avoided - a little too 'preppie' for some tastes perhaps. 
It should all remind us of childhood, sunshine, music heard on a transistor (probably Motown or Atlantic).  Yes?