need to escape an exam and I need HELP!!!!!!

Ok so I have an exam tomorrow which I can't fuck up. Any ideas to escape attending the exam would help, I need to a valid reason to tell my parents and teachers.

I know this might be stupid of me, but I have always been a straight-A student. However, I have lost interest in studying recently and there is no way I can start now and complete my syllabus. So if I attend this exam and mess it up my dad is going to kill me .

PLEASE HELP!!!!