Firstly, Robert please grow up.
Secondly, Monica i) I'm not at ACN & ii) at the end of day, you can wear whatever you want and your job performance will matter more but...business, and clients, are fickle. They often make first impressions and like tradition. So by wearing something unusual at work you are running the risk of getting yourself stereotyped. Its completely unfair and silly, I know, but if I was in that position I would rather not risk my career, however unimportant the reason is.
Perhaps the best thing to do would be to buy at least 1 dark suit and start the first week of work in that. Then it i) stops colleagues from stereotyping & ii) allows you to assess the situation.
By the way, if you interviewed in a pink suit then it's probably less of an issue!