Apparently Pink is for Princeses

I have a class of 5 girls who are fairly proficient in English. For example they ask "teacher meaning" of the word. So today I asked them what their favorite color is. So the common answer is yellow, purple and sky blue. I piped up and said my favorite is pink. They all promptly turned up their noses, crossed their fingers into an X and yelled NO NO NO. I asked why? Pink is for princess!! I thought all girls wanted to be princess...