Need a way to get out of dance tomorrow...?

As a dancer teacher myself, I would say just be honest with your teacher if you don't want to be there. Believe me, we have heard all the excuses a thousand times and most dance teachers can tell the difference between someone being off for a genuine reason, and someone who's just making excuses. To lie to your teacher is very disrespectful and I know from personal experience how hurtful and insulting it can be when you know a pupil is making up lies to get out of dancing.