The wavelength of the light reflected by the sippy cup doesn't bother him in the least. The liquid inside tastes just as good no matter what pigment is used to decorate the cup!
Sometimes I take him out in public with one of those cups. We get some looks, my camo-clad*, pink sippy-clutching lad and I. But I have to laugh, because one hundred years ago, pink was preferred for boys, because of its strong, masculine qualities. The author of the Bad Science blog quotes the fashion authorities of the time:
“There has been a great diversity of opinion on the subject, but the generally accepted rule is pink for the boy and blue for the girl. The reason is that pink being a more decided and stronger color is more suitable for the boy, while blue, which is more delicate and dainty, is prettier for the girl.” (Ladies' Home Journal, 1918)and
“If you like the color note on the little one’s garments, use pink for the boy and blue for the girl, if you are a follower of convention.” (The Sunday Sentinel, 1914)Somehow these colors got reversed around the time of World War II.
I felt a smile spread across my face when I read of someone else fighting against gender essentialism in a similar manner: Jeff from Feminist Allies carries a pink cell phone, and discusses the reactions his carrying of it elicits. I say, go Feminist Allies Jeff, go! It's a small thing but it makes people think about gender.
* Choices for 18-month-size boy's pants: forest camouflage (green), water camouflage (blue), desert camouflage (tan), khaki (usually cargo-style), jeans. My inner pacifist prefers the last two choices, however, I (not to mention my inner pacifist!) was not the one who purchased the majority of his clothes, and furthermore, there are more important things to worry about than the pattern on his pants. Plus, the contrast between the ultra-masculine camo and the ultra-feminine pink with purple accents sippy cup makes the act of being seen with both feel that much more subversive!