I bunked a 10 min detention?

it was for the whole of the 9th grade and my head of year demanded to see us after school for poor behavior during assembly and i went to the first one and we were naughty again but i bunked the second one. say if he wants to see me tomoz for it? thers 400 other kids in my year and im sure he wont notice im not ther and others bunked aswell but i need an accuse just incase i get busted