I need help

ok, people i need help so please post serious answers..

So, at the beggining of the day, my friends lost their lock and so i put my stuff and lock on their locker, as a friend. The day passed on.

Then at the end of the day i was the last person to leavethe classroom( detention) and when i got to their locker, my science project worth 40% of my school science mark was RIPPED UP, and i didnt hand it in yet!!

So, i took my lock back and put it on my locker, THEN : i took their gym clothes and compass box and thre it on teh floor. then my friend came up and he was like wtf is this stuff, and i told him, then he said cmon man be more bad dude! and he threw it all out, i didnt want to be like "uncool" so i let it be..... what shud i tell them?

answer PLEASE