The biggest mistake you have made during an exam?

Rs. 1 mistake costed Rs. 13000 and heck lot of hard work

One of my friends forgot to bring a BROWN PENCIL COLOUR in an anatomy exam. It is used to colour the muscles in the diagrams. He coloured them pink. And he got to reappear in the exam which costed around Rs. 13000 and had to read those 5 big anatomy books again.

Lesson learned: Every small detail is important in exam. You can't predict the mindset of teacher on the other side