I finally had a convention nightmare for Kumoricon 2010. I was at the con with some friends and we were at opening ceremonies, except I was in back rummaging through my luggage waiting to check in, and freaking out that my cosplays weren't done and wondering how this could have happened. Then my friend showed up late and I started yelling at her she didn't take in my ouran jacket like she promised she would and I needed it that night. I also forgot my camera, and money, and it was just a mess.
We walked over to our hotel to check in as opening ceremonies changes into a dance, and found a group of people freaking out about their cosplays and saying something was wrong. Then someone pointed out the date of the convention changed, and Kumoricon started early. Someone from staff ran by saying their was a situation, and then they made an announcement they screwed up the date, and apologized to everyone for starting a week early, and to come back in September.
It was odd. But I was glad I had more time for my cosplays. xD