Before the second wold war pink used to be THE boy's colour because it was said to be harsher on the eyes, since blue was seen as a gentle and subdued colour it was used on little girls. Notice how Alice in Wonderland wears blue? In the 1920's the blue used for sailor suits started to become an icon for masculinity (then of course the Japanese saw them and dressed school girls in them! ironic!) . Then when the second world war rolled around Hitler dressed gay prisoners in pink and deemed it a feminine and "weak" colour.
Personally I think a pink dress shirt under a nice dark suit jacket is a nice pop of colour and it looks pretty sharp!