Spoiling the fun?

Ok. I admit. I'm such a huge kill joy. :(( We were planing to go to one of my classmates house, have fun, eat, swim, and do other stuff but I said I wouldn't come. First,who wouldn't want to enjoy? Of course, I'd really like to come.But wait, I've got to set my priorities. Let's say it's just one day of fun and surely I'm gonna miss it but then again, I've got things to do. Sorry :( I know I can do 2 things without missing anything through time management. So, I'm gonna think about it first. Am I gonna go or not?