What did my girlfriend mean about rainbow kissing?

So yeah my girlfriend said yesterday morning before I went to work she wanted to try a rainbow kiss that night. So I bought some skittles on the way home and when I got through the door and said are you ready for your rainbow kiss and shook the bag of skittles you just sighed, got dressed up in a short skirt and heels and said she was going to see her sister. She wont answer my calls now. What did I do wrong?