Wow... what a sharp tongue! CD is a great platform for people to share resources, and to help each other. Everyone can be short of certain knowledge, which can be common sense to some others. If you happen to be the one who knows the answer, sincerely offer your help. Sarcasm is just not appreciated.
以后大家在读MBA的时候也会经常参加这种活动,有一个原则就是“It is always better to dress up than dress down”。人家如果没有对你有任何期待,而你穿的比较formal,是没问题的,还体现尊重;反之如果人家期待你formal,你太casual,那就有问题了。