Piping on polo shirts looks great. A contrasted piping (usually white) versus a dark colour is particularly pop-arty and Mod, borrowing and expanding from the original Fred Perry concept of contrasting piping on sleeves and collars, but picking out all the major details. The ones below are from Penguin, but there are lots of colourful alternatives to expensive Fred Perrys if you search on Atom Retro.
The other reason it’s cool is because Eddie in Lock Stock and Two Smoking Barrels wears one in the classic card game scene in which he loses half a million £. The soundtrack completes it, but his shirt remains pretty strong even as he walks out of the den in a debtor's daze.